CHEMICAL ESSAYS.
B Y
R. WATSON, D.D. F.R.S.
AND REGIUS PROFESSOR OF DIVINITY
THE UNIVERSITY OF CAMBRIDGE.
VOL* L
FOURTH EDITION.
LONDON:
PRINTED FOR T. EVANS,
PATERNOSTER-ROW,
MDCCLXXXVH,
T O
HIS GRACE
THE
DUKE OF RUTLAND,
MY LORD DUKE,
XT" OUR Grace, whilft I had
"*• the honour of being in-
truded with your Education in
this place, {hewed a difpofition
to the Study of Chemiftry : I wifh
that any thing contained in the
a 2 fol-
following Eflays may tend to re-
vive it.
Chemiflry is cultivated abroad
by perfons of the firft Rank,
Fortune, and Ability ; they find
in it a never-failing fource of
honourable amufement for their
private hours; and as public
men, they confider its cultivation
as one of the moft certain means
of bringing to their utmoft per-
fedion, the manufactures of their
country.
That
That your Grace's private
life may continue to be blefTed
with every domeftic comfort ;
and that your public life may be
diftingu iflied by principles and
actions ufeful to your country,
and honourable to yourfelf, is
the iincere prayer of
Your Grace's
Moft affectionate
And obliged Servant,
Feb. xo, r72i.
R. WATSON.
PREFACE.
THE fubjeds of the following
Effciys have been chofen, not
fo much with a view of giving a
Syftem of Chemiftry to the world, as
with the humbler defign of convey-
ing in a popular way, a general kind
of knowledge, to perfons not much
verfed in chemical inquiries.
Two other volumes, which are
nearly ready for the prefs, would
finifh the whole of my plan, but
being quite doubtful how far either
the fu eject itfelf, or at lead how far
the manner in which I have been
able to treat it, may be acceptable
to the Public, I dare not at prefent
venture to folicit the Reader's atten-
tion
vi PREFACE.
tion to them : If they fhould never
fee the light, the world will fuffer
little lofs -y and as to the trouble and
expence which I have been at in
competing them, they are more than
compenfated by the knowledge I
have gained.
There are two fets of men of
whom I particularly crave indul-
gence — Chemifts, and Divines.
Chemifts muft excufe me, as well
for having explained common mat-
ters, with what will appear to them
a difgufting minutenefs, as for hav-
..
ing paired over in filence fome of
the moft interefting queftions : fuch
are thofe which refpect the analyfis
of air and fire, the production and
,
tranfmutation of faline fubftances,
the fpontaneous deftruclion and ge-
neration of minerals.
Divines,
P R E F A C E. vii
Divines, I hope, will forgive^
me, if I have ftolen a few hours^
nor, I truft, from the duties of my
office, but certainly from the (Indies
of my profeftion, and employed,
them in the cultivation of natural
philofbphy: I could plead in my
defence, the example of fome of the
greateft characters, that ever adorned
either this Univerfity or the Church,
of England. The books of Nature
and of Revelation equally elevate
our conceptions and incite our)
piety; they mutually illuftrate each
other; they have an equal claim to
our regard, for they are both written
by the finger of the ONE ETERNAL
INCOMPREHENSIBLE GOD, TO WHOM
BE GLORY FOR EVER, AMEN.
For
viii PREFACE.
For the miflakes I may have fallen
into in treating of fuch a variety of
matter, and for the imperfection in
the defign and execution of the
Work itfelf, I generally intreat the
Reader's excufe in the words of
Piiny ;
Occupati Jumus officiis, fubfecivif-
que born ifta curamu$k
CON-
CONTENTS.
ESSAY
I. On the Rife and Progrefs of Che-
m'iflry page i
II. On the principal Terms and Opera-
tions ufed in Chemiftry 49
III. Of f aline Sitbjlances 109
IV. Of Fire, Sulphur ', and Phlogijton
149
V. Of the Origin of Subterraneous
Fires I8l
VI. Of Vitriols, and the reputed Vranf-
mutation of Iron into Copper
208
VII. Of Nitre or Saltpetre, and the
Application of its Acid to the
Inflammation of Oils and the
Congelation of guickfiher 247
VIII. Of
CONTENTS.
VIII. Of the Manner -of making Salt-
petre in Europe, and- of its Ge~
neration 2 83
IX. Of the Manner of making Salt-
fetre in the Eafl Indies 313
X. Of the Time when Gunpowder
was dif covered 327
ESSAY
ESSAY L
©N THE RISE AND PROGRESS OP
CHEMISTRY.
beginnings of every art,
JL which tended either to fupply
the neceffities, or to alleviate the
more preffing inconveniences of hu-
man life, were probably coeval with
the firfl eftablifhment of civil fo-
cieties, and preceded, by many
ages, the inventions of letters, of
hieroglyphics, and of every other
mode of tranfmitting to pofterity
the memory of pad tranfa&ions.
In vain lhall we inquire who in-
vented the firft plough, baked the
VOL, f. A firft
firft bread, fhaped the firft pot, wove
the firft garment, or hollowed out the
firft canoe. Whether men were ori-
giixally left, as they are at prefent, to
pick up cafual information concern-
ing the properties of bodies, and to
inveftigate by the ftrength of natural
genius the various relations of the
objects furrounding them ; or were,
in the very infancy of the world, fu-
pernaturally a (Tilled in the difcovery
of matters efTential,asitfhould feem,
to their exiftence and well-being,
muft ever remain unknown to us.
There can be little doubt that in
the fpace of, at leaft, 1656 years,
from the creation of the world to the
deluge, a great variety of economical
arts muft have been carried to a very
confiderable degree of perfection.
The knowledge of many of thefe pe-
rifhed,
( 3 )
rifhed, in ail likelihood, with the
then inhabitants of the earth -, it be-
ing fcarcely poflible for that fingle
family which efcaped the general
ruin to have either pra&ifed, or
been even fuperficially acquainted
with them aU. When men have
been long united in civil focieties,
and human nature has been exalted
by a reciprocal communication of
knowledge, it does not often hap-
pen, that any ufeful invention is in-
tirely loft : but were all the prefent
inhabitants of the earth, except
eight perfons, to be deftroyed by
one fudden calamity, who fees not
that mod of thofe fcrviceable and
elegant arts, which at prefent confli-
tute the employment, and contri-
bute to the happinefs of the greateft
part of the human race, would pro-
Aa bably
( 4 )
bably be buried in long oblivion ?
Many centuries might flip away,
before the new inhabitants of the
globe would again become ac-
quainted with the nature of the com-
pafs, with the arts of painting, print-
ing, or dying of making procelain,
gun-powder, fteel, or brafs.
The interval of time which elapfed
from the beginning of the world to
the firft deluge, is reckoned, by pro-
fane hiftorians, to be wholly uncer-
tain as to the events which happen-
ed in it: it was antecedent, by many
centuries, not only to the aera when
they fuppofed hiftory to commence,
but to the moft diilant ages of he-
roifm and fable. The only account
relative to it, which we can rely
upon, is contained in the firft fix
chapters of the book of Genefis ;
three of which being employed in
the
( 5 )
the hi/lory of the creation, and of
the fall of man; and a fourth con-
taining nothing but a genealogical
narration of the patriarchs from
Adam to Noah; it cannot reafon-,
ably be expected, that the other two
fhould enable us to trace the various
fteps by which the human intellect
advanced in the cultivation of arts
and fciences, or to afcerrain, with
much precifion, the time when any
of them was firft introduced into the
world. It is fomewhat remarkable
that from this account, fhort as it is,
the chemifts fhould be authorized,
with fome .propriety, to exalt the
antiquity of their art to the earlieft
times. Tubal-cain is there mention-,
ed as an inflructor of every artificer
in copper and iron*. This circum-
llance proves, beyond difpute, that
A3 one
* Gen, iv. 22*
one part of metallurgic chemiftrf
\vas well underftood at that time, for
copper and iron are of all the metals
mod difficultly extra&ed from their
ores, and cannot, even in our days,
be rendered malleable without much
Ikill and trouble; and itprovesalfo
that the arts in general were in an
improved ftate amongfl the antedi-
luvians. It is faid, indeed, that fome
tribes of Hottentots (who ean have
no pretenfions to be ranked amongft
the cultivators of the arts) know
how to melt both iron and copper-f;
but this knowledge of theirs, if they
have not derived it from an inter-
courfe with the Europeans, is a very
extraordinary circumftance, fince
the melting and manufacturing of
metals are juftly confidered, in ge-
neral,
f Forte's Voy. Vol. I. p. 81-
( 7 )
neral, as indications of a more ad-
vanced flate of civilization than the
Hottentots have yet arrived at. But
not to dwell upon this; Cain we
know built a city, and fome would
thence infer that metals were in ufe
before the time of Tubal-cain, and
that he is celebrated principally for
his ingenuity in fabricating them
for domeftic purpofes. Hiflory
feems to fupport our pretenfions
thus far. As to the opinion of thofe
who, too zealoufly contending for
the dignity of chemiflry, make the
difcovery of its myfleries to have,
been the fretium amoris which angels
paid to the fair daughters of men, we
in this age are more difpofed to apo-
logize for it than to adopt it. .We
may fay of arts what the Rornan
hiilorian has faid of Hates— datur
A 4 la*c
( 8 )
ia antiquitatiy uty mifctndo bu-
mana divixis, frimordia artium au-
guftiora faclat\.
For many ages after the flood we
have no certain accounts of the ftate
of chemiftry. The art of making
wine, indeed, was known, if not be-
fore, foon after the deluge -, this may
be collected from the intoxication
of Noah[j, there being no inebriat-
ing quality in the unfermented juice
of the grape. The Egyptians were
fkilled in the manufacturing of me-
tals, in medicinal chemiftry, and in
the art of embalming dead bodies,
long before the time of Mofes, as
appears from the mention made of
Jofeph's cup *, and from the phyfi-
cians being ordered to embalm the
body of Jacob f. They pradlifed
alfo
§ Li\7's Praef. || Gea. ix. 21.
* Gen. xliv. 2. f Gen. 1. 2.
( 9 )
alfo the arts of dying and of making
coloured glafs at a very early pe-
riod $ as has been gathered, not only
from the teflimony of Strabo, but
from the relics found with their
mummies, and from the glafs beads
with which their mummies are
fometimes ftudded f. But we cannot
from thefe inflances conclude that
chemiftry was then cultivated as a
feparate branch of fcience, or dif-
tinguifhed in its application, from
a variety of other arts which mud
have been excrcifed for the fupport
and convenience of human life. All
of thefe had probably fome depend-
ance on chemical principles, but
they
f See Deleval's ingenious Inquiry into the
Caufe of the Changes of Colours, Pref. LV 1 :
and Duten's learned Inquiry into the Difco-
•'veries attributed to the Moderns, p. 241.
( .10 )
they were then, as they are at
feot, p race i fed by the feveral ar-
tifts without their having any theo-
retical knowledge of their refpec-
tive employments. Nor can we pay
much attention in this inquiry to the
obfcure accounts which are given
of the two great Egyptian philofo-
phers, Herrnes the elder, fuppofed
to be the fame with Mizraim grand-
fon of Noah 3 and Hermes furnamed
Trifmegiftus the younger, from
•whom chemiftry has by fome been
affectedly called the Hermetic art.
The chemical (kill of Mofes dif-
played in his burning, reducing to
>a.n. impalpable powder, and render-
ing potable the golden calf in the
\vijdernefs, has been generally ex-
tolled by writers on this fubjcftj and
-conffontly adduced as a proof of the
then
3
( II )
then flourifhing flate of chemiftry
amongft the Egyptians, in whofe
learning he is faid to have been well
verfed. If Mofes had really reduced
the gold of which the calf con fitted,
into afhes, by calcining it in the
fire ; or made it any other way folu-
ble in water, this inftance would
have been greatly in point -, but nei-
ther in Exodus nor in Deuteronomy
where the fact is mentioned, is there
any thing faid of its being diifolved
in water. The enemies of revelation,
on the other hand, conceiving it to
be impoflible to calcine gold, or to
render it potable, have produced
this account as containing a proof
of the want of veracity in the facred
hiflorian. Both fides feem to be in
an error ; Stahl and other chemiits
have (hewn that it is poffible to make
gold
gold potable, but we have no rea-
fon to conclude that Mofes either
ufed the procefs of Stahl, or any
other chemical means for effecting
the purpofe intended — be took the
calf which they had made, and burnt it
in the fire, and ground if to powder, and
ftrewed it upon the water, and made
the children of IJrael to drink of it *.
Here is not the leaft intimation given
of the gold having been diflblved,
chemically fpeaking, in waters it was
{lamped and ground, or, as the Arabic
and Syriac verfions have it, filed into
a fine duft, and thrown into the river
of which the children of Ifrael ufed
to drink : part of the gold would
remain, notwithftanding its greater
fpecific gravity, fufpended for a time
(as happens in the walhing of cop-
per
* Excel, xxxii. 20.
( 13 )
per and lead ores), and might be
fwallowedin drinking the waters the
reft would fink to the bottom, or
be carried away by the flux of the
ftream.
Neverthelefs, though nothing fa-
tisfactory can be concluded concern-
ing the Egyptian chemiftry from
what is faid of Mofes in this in-
ftance, yet the flrucliure of the ark,
and the fafhion of Aaron's garments,
clearly indicate to us that the arts of
manufacturing metals, of dying lea-
ther red, and linen blue, purple,
and fcarlet; of diftinguiihing preci-
ous ftones, and engraving upon them,
were at that time practifed in a very
eminent degree*. The Ifraelites
had unqueftionably learned thefe
arts in Egypt, and there is great rea-
fon
* Exod. xxvi. and xxviii.
( '4 )
ion to fuppofc not only that learning
of every kind firft flourifhed in,
Egypt, but that chemiftry, in parti-
cular, was much cultivated in that
country when other fciences -had
pa{Ted into other parts of the world.
Pliny, in fpeaking of the four periods
of learning which had preceded the
times in which he lived, reckons the
Egyptian the firft : and Suidas, who
"fc thought to have lived in the tenth
century, informs us that the Empe-
ror Diocletian ordered all the books
of chemiflry to be burned, left the
Egyptians learning from them the
art of preparing gold and filver,
Ihould thence derive refources to op-
pofe the Romans * . It is worthy of
notice that Suidas ufes the word
chemiftry in a very reftricled fe-nfe,
when
Lexicon,
( '5 )
when he interprets it by — -the pre-
paration of gold and filver j — but all
the chemifts in the time of Suidas,
and for many ages before and after
him, were alchemifts. The edict of
Diocletian in the third century, had
little effect in reprefling the ardour
for this ftudy in any part of the
world, fince we are told that not
lefs than five thoufand books, to fay
nothing of manufcripts, have beetf
published upon the fubject of al-
chemy fince his time *.
'At what particular period this
branch of chemiftry, refpecting the
tranfmutation of the bafer metals
into gold, began to be diflinguifhed
by the name of alchemy, cannot
be determined. An author of the
fourth century, in an aftrological
work,
* Chem. Waller, p. 40.
work, fpeaks of the fciencc of al-
chemy as well underftood at that
time; and this is faid to be the firft
place in which the word alchemy is
ufed *. But Vofiius aflerts that we
ought, in the place here referred to,
inftead of alcbemia to read cbemla f :
be this as, it may, we can have no
doubt of alcbemia being compound-
ed of the Arabic al (the) and chemia,
% to denote excellence and fuperiority,
4 as in al-manack, al-koran, and other
words. Whether the Greeks in-
vented^ or received from the Egyp-
tians, the do&rine concerning the
tranfmutation of metals, or whether
the Arabians were the firft who pro-
fefied it, is uncertain. To change
o
iron,
* Jul. Fermi. Mater. Allronomicon. Lib,
III. c. 15.
\ Vofe. Etymo, Vox Alchemia.
( '7 )
iron, lead, tin, copper, quickfilver
into gold, feems to be a problem
more likely to animate mankind to
attempt its folution, than either that
of fquaring the circle, or of finding
out a perpetual motion; and as it
has never yet been proved, perhaps
never can be proved to be an imp of-
Jtble problem, it ought not to be
efteemed a matter of wonder, that
the firft chemical books we meet
with, are almoft intirely employed
in alchemical inquiries.
Chemiftry^ with the reft of the
iciences, being banifhed from the
other parts of the world, took re-
fuge among the Arabians. Geber
in the feventh, or as fome will have
it in the eighth, and others in the
ninth century, wrote feveral chemi-
cal or rather alchemical books in
Arabic. In thefe works of Geber
VOL. i. B are
are contained fuch ufeful directions
concerning the manner of conduct-
ing diilillation, calcination, fubli-
mation, and other chemical opera-
tions, and fuch pertinent obferva-
tions refpecting various minerals, as
juftly feem to entitle him to the cha-
racter, which fome have given him,
of being the father of chemiftry ;
though, in one of the mod celebrated
of his works, he modeltly acknow-
ledges himfelf to have done little
elfe than abridge the doctrine of the
ancients concerning the tranfmuta-
tion of metals *. Whether he was
pre-
* Totam noftram metallorum tranfmu-
tandorum fcientiam, quam ex libris antique-
rum philofophorum abbreviavimus, compi-
latione diverfa, in noftris voluminibus, hie
in unam fummam redegimiis. Gebri Alch.
cap. i. -edition by Zetzner' in 1512. In
Tancken's edition in 1681, the words me-
tallorum traafmutandorum are omitted.
( 19 )
preceded by Mefue and Rhazes, or
followed by them, is not in the pre-
fent inquiry a matter of much im-
portance to determine, fince the
forementioned phyfieians as well as
Avicenna, who, from all accounts*
was pofterior to Geber, fpeak of
many chemical preparations, and
thus thoroughly eftablifh the opi-
nion, that medical chemiltry, as well
as alchemy, was in thofe dark ages
well underftood by the Arabians.
Towards the beginning of the
thirteenth century Albert the great
in Germany, and Roger Bacon in
England, began to cultivate che-
miitry with fuccefs, excited there-
to, probably* by the perufal of fome
Arabic books, which about that
time were tranflated into Latin.
Thefe two monks, efpecially the
B a latter,
latter, feem to have as far exceeded
the common ftandard of learning in
the age in which they lived, as any
philofophers who have appeared in
any country either before their time
or fmce. They were fucceeded in
the fourteenth and fifteenth centu-
ries, by a great many eminent men
both of our own country and fo-
reigners, who, in applying them-
felves to alchemy, made, inciden-
tally, many ufeful difcoveries in va-
rious parts of chemiftry : fuch were
Arnoldus de Villa Nova in France;
our countryman George Ripley;
Raymund Lully of Majorca, who
firfl introduced, or at Jeafl more
largely explained, the notion of an
univerfal medicine; and Bafile Va-
lentine, whofe excellent book, inti-
tied Currus Antimonii triumph alls, has
contributed more than any thing
clfc
elfe to the introduction of that molt
ufcful mineral into the regular prac-
tice of mod phyficians in Europe;
it has given occafion alfo to a va-
riety of beneficial, as well as (a cir-
cumftance which might be expect-
ed, whenfo tickliih a mineral fell in-
to the hands of interefted empirics)
to many pernicious noftrums. To
this, rather than to the arrogant fe-
verity with which Bafile Valentine
treats the phyficians his cotempora-
ries, may we attribute the cenfure of
Boerhaave, who, in fpeaking of him,
fays, " he erred chiefly in this, that
he commended every antimonial
preparation, than which nothing
can be more foolifh, fallacious, and
dangerous; but this fatal error has
infected every medical fchool from
that time to this*." The
* Boerh. Ch. Vol. I. p. 18.
B3
The attempting to make gold or
filver by alchemical procefTts had
been prohibited by a conftitution of
Pope John the XXIId. who was ele-
vated to the pontificate in the year
13^6*; and within about one hun-
dred and twenty years from the death
of friar Bacon, the nobility and gefi-
try of England had become fo infa-
tuated with the notions of alchemy,
and wafted fo much of their fub-
ftance in fearch of the philofopher's
ftone, as to render the interpofition
of government neceffary to reftrain
their folly. The following act of
parliament, which lord Coke calls
the fhorteft he ever met with, was
pnfled 5 H. 4. cc None from hence-
forth (hall ufe to multiply gold or
filver^ or ufe the craft of multiplica-
tion,
* Kirch, Mun. Sub, L. xi. Seft, iv. c. i,
( 23 )
tion, and if any the fame do, he fhall
incur the pain of felony." It has
been fuggefted, that the reafon of
pafting this adt was not an appre-
henfion left men Ihould ruin their
fortunes by endeavouring to make
gold, but a jealoufy left government
Jhould be above afking aid of the
fubjecT:. " After Raymund Lully,
and Sir George Ripley, had fo large-
ly multiplied gold, the lords and
commons, conceiving fome danger
that the regency, having fuch im-
meufc treafure at command, would
be above afking aid of the fubject,
and might become too arbitrary and
tyrannical, made an act: againft mul-
tiplying gold and filver V This
acl, whatever might be the occafion
of parTing it, though it gave fome
B 4 ob-
* Opera Mineralui cxpHcata, p. 10.
obftru&ion to the public exercife of
akhemy, yet it did not cure the dif-
pofition for it in individuals, nor re-
move the general credulity ; for in
the 35 H. 6. Letters Patent were
granted to feveral people, by which
they were permitted to inveitigate aa
univerfal medicine, and to perform
the tranfmutation of metals into real
gold and filver, with a non-obftante
of the forementioned flatute, which
remained in full force till the year
1689, when being conceived to ope-
rate to the difcouragement of the
melting and refining of metals, it was
formally repealed *.
The
* Mr. Boyle is faid by his intereft to have
procured the repeal of this lingular flatute,
and to have been probably induced thereto,
in confequence of his having been perfuaded
of the poffibility of the tranfmutation of me-
tals into gold. See his life prefixed to the
folio ed, of his works, p. 83.
The beginning of the fixteenth
century was remarkable for a great
revolution produced in the Europe-
an practice of phyfic, by means of
chemiftry. Then it was that Para-
celfus, following the Heps of Bafile
Valentine, and growing famous for
curing the venereal difeafe, the le-
profy, and other virulent diforders,
principally by the means of mercu-
rial and antimonial preparations,
wholly rejected the Galenical phar-
macy, and fubftituted in its flead the
chemical. He had a profeflbr's chair
given him by the magiftracy of Ba-
HI, was the firft who read public lec-
tures in medicine and chemiftry,
and fubjefted animal and vegetable
as well as mineral fubftances to an
examination by fire.
It feldom happens that a man of
but common abilities, and in the
moft
mofl retired fcenes of life, obferves
iuch a ft rift uniformity of conduct,
as not to afford prejudice and par-
tiality fufficient materials for draw-
ing his character in different colours ;
but fuch a great and irregular genius
as Paracelfus, could not fail of be-
coming alike, the fubjecl: of the ex-
tremes of panegyrick and fatire. He
has accordingly been efteemed by
fome, a fecond Efculapius -, others
have thought that he was pofTefied of
more impudence than merit, and that
his reputation was more owing to
the brutal fingularity of his conduct,
than to the cures he performed. He
treated the phyficians of his time,
with the mofl fottifh vanity and il-
liberal infolence ; telling them, that
the very down of his bald pate had
more knowledge than all their wri-
ters,
ters, the buckles of his fhoes more
learning than Galen or Avicenna,
and his beard more experience than
all their univerfities *, He revived
the extravagant doctrine of Ray-
mund Lully, concerning an univer-
fal medicine, and untimely funk into
his grave at the age of forty-feven^
whilft he boafted himfelf to be in
pofTefiion of fecrets able to prolong
the prefent period of human life to
that of the Antediluvians.
But in whatever eftimation the
merit of Paracelfus as a chemift may
be held, certain it is, that his fame
excited the envy of fome, the emu-
lation of others, arid the induftry of
all. Thofe who attacked, and thofc
who defended his principles, equally
promoted
* Preface to his book entitled Paragranum,
where there is mor^ in the lame flyle.
( 23 )
promoted the knowledge of die-
miftry; which from his time, by
attracting the notice of phyficians>
began every where to be fyftemati-
cally treated, and more generally
underftood.
Soon after the death of Paracelfus,
which happened in the year 1541,
the arts of mining and fluxing me-
tals, which had been praftifed in
mod countries from the earl i eft
times, but had never been explain-
ed by any writers in a fcientific man-
ner, received great illuftration from
the works of Georgius Agricola, a
German phyfician. The Greeks and
Romans had left no treatifes worth
mentioning upon the fubjecl, and
though a book or two had appeared
in the German language, and one in
the Italian, relative to metallurgy,
before
before Agricola publiflied his twelve
books De Re Metallica, yet he is
juftly efteemed the firft author of re-
putation in that branch of chemiftry.
Lazarus Erckern (aflay - mailer
general of the empire of Germany)
followed Agricola in the fame pur-
fuit. His works were firft publiih-
«d at Prague in 1574, and an En-
glifh tranflation of them by Sir John
Pettus, came out at London in
1683. The works of Agricola and
Erckern are ftill highly efteemed,
though feveral others have been
publifhed, chiefly in Germany, upon
the fame f\ibje6t fmce their time.
Amongft thefe we may reckon
Schindler's Art of AfTaying Ores
and Metals ; the metallurgic works
ofOrfchall; the works of Henckell;
of Sclutterj of Cramer , of Lehman;
and
( 30 )
and of Gellert. Germany, indeed,
has for a long time been the great
fchool of metallurgy for the reft of
Europe; and we, in this country,
owe the prefent flourifhing condi-
tion of our mines, efpecially of our
copper mines, as well as of our brafs
manufactory, to the wife policy of
queen Elizabeth, in granting great
privileges to Daniel Houghfetter,
Chriftopher Schutz, and other Ger-
mans; whom Ihe had invited into
jLngland, in order to inftrucl: her
fubjects in the art of metallurgy.
It was not, however, till towards
the middle of the laft century, that
general chemiftry began to be culti-
vated in a liberal and philofophical
manner. So early as the year 1645
feveral ingenious perfons in London,
in order to divert their thoughts
from
( 3' )
from the horrors of the civil war
which had then broken out, had
formed themfdves into a fociety,
and held weekly meetings, in which
they treated of, what was then called,
the new or experimental philofo-
phy. Thefe meetings were conti-
nued in London till the eftablifh-
ment of the Royal Society in 1662 ;
and before that time, by the re-
moval of fome of the original mem-
bers to Oxford, fimilar meetings
were held there, and thofe fludies
brought into repute in that univer-
fity. Mr. Boyle, who had entered
upon his chemical fludies about
the year 1647, was a principal per-
fon in the Oxford meetings: he
publifhed at that place his Scepti-
cal Chemift, in 1661, and by his
various writings and experiments
greatly
4
( 3* )
greatly contributed to the intro-
ducing into England, a tafte for ra-
tional chemiftry.
Next to Boyle, or perhaps before
him as a chemifl, (lands his cotem-
porary the unfortunate Beccher,
whofe Ploy fit a Subterranea, juflly in-
titled opus fine fariy was firft pub-
liflied in 1669. After having fuf-
fered various perfecutions in Ger-
mafny, he came over into England,
and died at London in 1682, at the
age of 57. He refided fome time be-
fore his death in Cornwall, which
- he calls the mineral fchool, owning
that from a teacher, he was there
become a learner. He was the au-
thor of many improvements in the
manner of working mines, and of
fluxing metals -9 in particular he firft
introduced into Cornwall the me-
thod
( 33 )
< thod of fluxing tin by means of the
.flame of pit-coal, inftead of wood
or charcoal *.
Lemery's very accurate courfe
-of practical chemiftry appeared in
1675.
* Beccher wrote his Alphabethum Mine-
rale, at Truro in Cornwall, in 1682, not
long before his death. In his dedication of
this tract to Mr. Boyle, he has the following
words : — " ignis ufus, ope, flammarum li-
thantracum ftannum et mineralia fundendi,
•Cornubiae hactenus incognitus, fed a me in-
troductus." — This account which Beecher
gives of himfelf, is not quite agreeable to
what is advanced by an author every way
•qualified to come at the truth of this mat-
ter.— " Neceffity at laft fuggefted the in-
troduction of pit-coal for the imelting of tin
ore ; and among others, to Sir Bevil Gran-
ville "of Stow in this count}', temp. Car. I.
who made feveral experiments, though with-
out fuccefs ; neither did the effectual fmelt-
ing of tin ore with pit-coal, take place till
*he fecond year of Queen Anne." Pryce's
Miner. Cornub. p. 282.
VOL. i. C
C 34 )
1675. Glauber's works had been
publiflied at different times, from
1651 to 1661, when his trad:, enti-
tled Philofophical Furnaces, came
out at Amfterdam. Kunckel died
in Sweden in 1702 ; he had prac-
tifed chemiflry for above 50 years,
under the aufpices of the elector of
Saxony, and of Charles XL of Swe-
den. He wrote his chemical obfer-
vations in the German language,
but had them tranilated into Latin
in the year 1677; the tranflation is
dedicated by its author to our Roy-
al Society. They were afterwards
translated into Englifh in 1704.
Having had the fuperintendency of
feveral glafs-houfes, he had a fine
opportunity of making a great va-
riety of experiments in that way ;
and I have been informed by our
ena-
( 33 )
•enamellers, and makers of artificial
gems, that they can depend more
-upon the procefFes and observations,
-of Kunckel, than of any other author
upon the fame fubjedt. The chemi-
cal labours of thefe and many other
eminent men, too numerous to men-
tion, were greatly forwarded by the
'Cftablifhment of feveral focieties,
for the encouragement of natural
philofophy, which took place in
various parts of Europe about that
period.
The Philefophical Tranfadions
at London,, the Hiiroire de T Aca-
deniie Royale des Sciences at Paris,
the Saggi d'Efperienze di Acad. del
Cimento at Florence, the Journal
des Scavans in Holland, the Ephe-
merides Academic Naturae Curio-
forum, in Germany, the A'd:s of the
C 2 Academy
( 36 )
Academy of Copenhagen, and the
Acta Eruditorum at Leyplic ; all
thefe works began to be publilhed
within the fpace of twenty years
from 1665, when our Royal So-
ciety firfl fet the example, by pub-
lilhing the Philofophical Tranfac-
tions. To thefe may be added, the
works of the Academies of Berlin,
.Peterfburgh, Stockholm, Upfal,
Bononia, Bourdeaux, Montpelier,
Gottingen, and of feveral others
which have been eftablilhed within
the courfe of the prefent century.
Near a thoufand volumes have been
publifhed by thefe learned focieties
within lefs than 120 years. The
number of facts which are therein
related refpe&ing chemiftry, and
every other branch of natural philo-
fophy, is exceedingly great ; but the
fubjecl:
( 37 )
fubjedt is flill greater, and muft for
ever mock the efforts of the human
race to exhauft it. Well did Lord
Bacon compare natural philofophy
to a pyramid ! Its bafis is indeed the
hiflory of nature, of which we know
a little and conjecture much ; but
its top is, without doubt, hid high
among the clouds ; it is " the work
which God worketh from the beginning
to the end" infinite and infcrutable.
By the light which has been
incidentally thrown upon various
parts of chemiflry from thofe vaft
undertakings of publick focieties, as
well as from the more exprefs la-
bours of Stahl, Newman, Hoffman,
Juncker, Geoffry, Boerhaave, and of
many others equally worthy of com-
mendation ; by the theoretic con-
clufions and fyftematic divifions
C 3 which
C 58 )
which have been introduced into it ^
from the didaxTtic manner in which
the {Indents of this art have been
inflructed in every, medical fchool^
chemiiiry has quite changed its ap-
pearance. It is no longer confi-
dered merely in a medical view,,
nor reftri&ed to fome fruitlefs ef-
fonts upon metals ; it no longer at-
tempts to impofe upon the credulity
of the ignorant, nor affects to aflo^
nifh the fimplicity of the vulgar by
its wonders, but is content with ex-
plaining them upon the principles
of found philofophy. It has fhaken
off the opprobrium which had been
thrown upon it, from the unintelli-
gible jargon of the alchemifls, by
revealing all its fecrets in a lan-
guage as clear and as common as the
nature of its fubjects and operations
will admit. Con-
( 39 )
Confidered as a branch of phy-
licks, chemiltry is but yet in its in-
fancy : however, the mutual emu-
lation and unwearied endeavours
of fo many eminent men as are in
every part of Europe engaged in its
cultivation, will in a little time ren-
der it equal to any part of natural
philofophy, in the clearnefs and fo*
iidity of its principles. Jn the uti-
lity refulting to the public from
its concluiions, with refpect to the
practice of medicine, of agricul-
ture, arts and manufactures of every
kind, it is even in its prefent ftate
inferior to none.
The ufes of chemiftry, not only
in the medical, but in every econo-
mical art are too extenfive to be
enumerated, and too notorious to
want illuilration ; it may juft be ob-
C 4 ferved,
( 40 )
ferved, that a variety of manufac-
tures, by a proper application of
chemical principles, might, proba-
bly, be wrought at a lefs expence,
and executed in a better manner
than they a-re at prefent. But to
this improvement there are impe*
diments on every hand, which can-
not ealily be overcome. Thofe who
by their fnuations in life are re-
moved from any defign or deiire
of augmenting their fortunes by
making difcoveries in the chemical
arts, will hardly be induced to di-
minilh them by engaging in expen-
five experimental inquiries, which
not only require an uninterrupted
attention of mind, but are attended
with the wearifomenefs of bodily la-
bour. It is not enough to employ
operators in this bufmefs; a man muft
blacken*
( 41 )
blacken his own hands with chap,
coal, he muft fweat over the furnace,,,
and inhale many a noxious vapour
before he can become a chemift..
On the other hand, the artifls them-
felves are generally illiterate,, timid,
and bigoted to particular modes of
carrying on their refpe&ive opera-
tions. Being unacquainted with the
learned, or modern, languages, they
feldoni know any thing of new dif-
eovcries, or of the methods of work-
ing practifed in other countries. De-
terred by the too frequent, but
much-to-be lamented examples of
thofe, who, in benefiting the public
by projects and experiments, have
ruined therafelves, they are unwil-
ling to incur the leaft expence in
making trials, which are uncertain
with refpecl: to profit. From this ap-
prehenfiort
( 4* )
prehenfion, as well as from the myf-
terious manner in which mod arts,
before the invention of printing,
and many ftill continue to be taught,
they acquire a certain opinidtrete,
which effectually hinders them from
making improvements, by depart-
ing from the ancient traditionary
precepts of their art. It cannot be
queflioned, that the arts of dying,
painting, brewing, difiilling, tan-
ning, of making glafs, enamels,
porcelane, artificial {lone, common
fait, fal ammoniac, falt-petre, potafh,
fugar, and a great variety of others,
have received much improvement
from chemical inquiry, and are ca«-
pable of receiving much more.
Metallurgy in particular, though
one of the mod: ancient branches of
chemiftry, affords matter enough for
new
( 43 )
new difcoveries. There are a great
many combinations of metals whicfo
have never been made ; many of
which, however, might be made,
and in fuch a variety of proportions,,
as, very probably, would furnilh us
with metallic mixtures more fer^
viceable than any in ufe* The me-
thod of extracting the greateft pof-
fible quantity of metal from a given-
quantity of the fame kind of ore,
has, perhaps, in no one inftance been;
afcertained with fufficient precifion..
There are many forts of iron and
copper ores which cannot be con-r
verted into malleable metals, with-
out much labour, and a great ex^
pence of fuel ; it is very probable,,
that by a well -conducted feries of
experiments, more compendious
Ways of working thefe minerals-
might
( 44 )
t r j T
be found out. In our own
times three new metallic fubftances
have been difcovered *, and their
properties abundantly afcertained
by experiment; and it may reafon-
ably be conjectured, that future ex-
perience will yet augment their
number. Till Marggraaf ihewed the
manner of doing it, no metallic fub-
ftance could be extracted from ca-.
lamine, and all Europe was fupplied
with zinc -j~ either from India or
from Germany. A manufactory of
this metallic fubftance has not many
years ago been eftabliihed in our
own country, and the copper works
near Briflol have fupplied Birming-
ham
* Platina, Reguhis of Cobalt, Nickel.
f Zinc is a metallic fubftance, of the colour
of lead ; when united with copper, it coniti-
tutes brafs, pinchbeck, and other metallic
mixtures refembling gold.
( 45 )
ham with zinc extracted from ca-
lamine. Black jack was not long
fince employed in Wales for mend-
ing the roads; its value is not yet
generally known in Berbyfhire ; but
it is now well underflood by fome
individuals to anfwer the purpofe of
caiamine for the making of brafs *.
Monf. Von Swab in 1738 was, I be-
lieve, the firft perfon who diflilled
zinc from black-jack-^; and a work
which he eredtedy probably gave the
hint to the eftabliihers of our Eng-
lifli manufa&ory : indeed, I have
been well informed, that they pur-
chafed the fecret from him when he
was
* The cobalt ores in Hefie, which at pr,e-
fent produce a net profit of about 14000!. a-
year, were formerly ufed for the fame purpofe
as black-jack was lately in Wales. — Born*s
Travels by Rafpe, Pre. xxvi.
f Cronftedt's Miner. Sec. 231.
( 46 )
in England. The various kinds
of black lead, from which neither
tin nor iron can at prefent be pro-
cured to advantage ; the mundicks,
fome cobalt ores, cavvk, kebble, and
other mineral fubflances, which are
now thought to be ufelefs, may fome
time or other, perhaps, be applied
to good purpofe. Cavvk and kebble,
•which are found in grrat quantities
in mining countries, efpecially in
Derbyshire, and which are univer-
fally thrown away, may, perhaps,
be nothing but different kinds of
fpar, and deftitute of all metallic
matter * ; yet it may not be impro-
per to remark, that the external ap-
pearance of the yellowilh cawk is
wholly fimilar to that of calcined
black-
* See Mr. Wotilfe's ingenious Experiments
iaPhilof. Tranf. 1779, P» JS'
( 47 )
black-jack. That it is much of the
fame weight as black-jack may ap-
pear from the annexed table :
Weight of a cubic foot of
White cawk 404^
Yellow cawk 4112
Kebble 4319} avoirdup. oz.
Black-jack 4°93/
Water icocj
In a word, the improvement of
metallurgy, and the other mechanic -
arts dependent on chemiftry, might
beil be made by the public eftablifh-
ment of an Academy, the labours of
which fhould be deflined to that
particular purpofe. The utility of
fuch eitablilhments has been expe-
rienced in Saxony and other places ;
and as mines and manufactures are
to the full as important to us, as to
any other European ftate, one may
4 hope,
( 48 )
liope, that the conftituting a Cbemi-
•cal Academy may, in times of peace
and tranquillity, become an objed:
not unworthy the attention of the
King or the Legiflature of the
Britiih nation*.
* The reader who wifhes to become more
fully acquainted with the hiftory of chemiftry,
may confult what Borrichius has faid in his
Difiertation de Ortn et ProgrefTu Chemise, pub-
lifhed at Copenhagen in 1668; and in his
t>ook entitled Hermetis, JLgyptiorum, et Che-
micorum fapientia ab Hermanni Couringii ani-
inadverfionibus vindicata, publifhed at the
fame place in 1674. He will alfo find fome-
thing worth his notice on this fubjecl in Boer-
haave's Chemiftry ; and in a work of Walle-
rius, called, Chemis Phyficas Pars Prima, pub-
limed at Stockholm in 1760; where there is
an ufeful catalogue of the mofl approved
writers on the various parts of chemiftry.
ESSAY
ESSAY II.
ON THE PRINCIPAL TERMS ANI>
OPERATIONS USED IN CHEMISTRY.
THIS EfTay, in which I mean
to give a general account of
the principal terms and operations
ufed in chemiftry, will, perhaps, be
more troublefome to the reader, than
any other which I fhall have occafioti
to write : but he mufl not be dif-
couraged, nor conceive a difguft
againft the fcience itfelf, from an
inconvenience neceflarily attending
all fciertces. Chemiftry has as few
technical terms belonging to it, as
navigation, law, medicine, or any
other art or fcience, which may have
VOL. i. D chanced
( 50 )
chanced to engage his attention.
The more ancient chemifts, indeed,
were fond of coining abftrufe terms,
and frequent in the ufe of them ;
but this affectation is, at prefent,
pretty generally and very juftly ex-
ploded.
OF SOLIDITY AND FLUIDITY.
Though, in philofophical pro-
priety of fpeech, water be as folid a
body as a diamond, yet in the com-,
mon acceptation of the word foli-
•dity, we confider it as oppofed to
fluidity. Natural philofophers have
agreed to call that, principle, by
which the condiment parts of flones,
glafs, metals, and other fubflances
cohere together, Attraction. They
illuilrate the agency of this princi-
ple, by a variety of decifive experi-
ments ;
( 5' )
ments ; decifive as to the proof of
the exiftence of fuch a power, but
indicating nothing at all of the caufe
of it. As the unknown principle
of mutual attraction between the
conftituent parts of folid bodies, is
the caufe of their/<?//^Vy, fo the un-
known principle of fire, is the caufe
of \hz\rfiiiidity. I call the princi-
ple of fire unknown, bctaufe, though
its effects are fufficiently manifeft,
the caufe of it is wholly queftion-
able. But in whatever manner fire
may be fuppofcd to exert its agen-
cy, it feems to be the great inftru-
ment of fluidity upon the furface of
the earth. Without a certain degree
of heat, water, fpirits of wine, oil,
quickfilver, and perhaps the air it-
felf, would be converted into folid
bodies 5 and with a certain degree
D 2 of
( 5* )
of heat all fluid bodies would be
changed into elaftic vapours, and all
folid bodies would either be wholly
difiipated, or in part difiipated, and
in part converted into fluid glafs.
Thefe are extreme cafes, to which
no portion of the earth is obnoxious ;
no climate is fo hot, but that it
abounds with water in a date of flui-
dity ; and none has yet been difco-
vered fo cold, but that the air and
the blood, of aquatic animals at
leaft, continue fluid in it.
OF VOLATILITY AND FIXITY.
The changes produced in bodies
by the action of fire are various, ac-
cording to the conftitution of the
bodies themfelves, and the degree
of heat to which they are expofed.
Some bodies, in a certain degree of
heatf
( 53 )
heat, may be wholly diffipated, others
only in part, others not at all. Thus
the fame degree of heat which will
intirely ditfipate camphor, and con-
vert water into vapour, will only-
produce a partial difperfion of the
conftituent principles of turpentine,,
blood, or milk; and will not effect
any change or diminution of weight,
in feveral woods, metals, earths,,
falts, and oils. Thofe bodies which
by heat fuffer no diminution of their
weight, are faid t&bejixed, and thofe-
which do lofe of their weight, are-
faid to be volatile j and they are faid
to be more or lefs volatile, according-
as a lefs or a greater degree of heat
is requifite for producing a fepara-
tion of their parts, It is obvious,,
that volatility belongs to mofb bo-
dies, folid as well as fluid j fince the
D 3
( 54 )
heat of the atmofphere is fufficient
to diminifh the weight of many, and
artificial applications of fuperior de-
grees of heat, that of many more :
but it is not certain, whether abfo-
\utzjixity belongs to any body in na-
ture, fince the fame body which is
fixed in one degree of heat, may be-
come volatile in another : thus dia-
monds, which remain unchanged in
a fmall degree of heat, may be wholly
diffipated in open veffels by a great-
er j and gold, which can refift the
moil violent fires excited in our fur-
naces, without lofing any thing of its
weight, may not be able to fuftain
the fiercer action of the folar rays,
when united in the focus of a large
burning-glafs.
The fixity of bodies is not in pro-
portion to their hardnefs, for a dia-
mond.
( ss )
mond is harder than a ruby, yet a dia-
mond may be wholly diflipated by a
degree of heat which produces no
manner of change in a ruby. We are
indebted to the Emperor Francis I.
for this experiment. He put dia-
monds and rubies, to the worth of
fix thoufand florins, into different
veflels, andexpofed them to a violent
fire for 24 hours ; at the end of that
time the vefiels were taken out of the
fire and opened, and there was not
remaining the lead veftige of the
diamonds, the whole had been difli-
pated ; but the rubies were found ta
have undergone no fort of change,
either with rcfpect to colour, Hiapc,
or weight§. OF
§ See Magafin cle Hambourg/ Tom. xviii.,
p. 164. or an extract in the notes annexed to
Henckel's Work*, publifhed at Paris in 1760,
VoL II. p. 413.— Similar experiments have
B 4 lat£l/
( 56 )
OF EVAPORATION, VOLATILIZATION,
EXHALATION.
"When folid or fluid bodies fuffer
a diminution of their weight* the
parts which become volatile and fly
away, are faid to be evaporated, vola-
tilized, exhaled) for thefe three terms
are often ufed promifcuoufly, though
it would be an eafy matter to diflin-
guifh them. The parts themfelves
are either humid, fuch are thofe
which are feparated from all fluids
(except quickfilver), and the watery
parts of folid bodies; or they are
dry $ fuch are the volatile parts fepa-
rated from marble or chalk, during
the burning of lime, from volatile
falts,
lately been made in France : See Chymie par
M. Baume, Vol. I. p. 105. A good tranilation
of this excellent work is much wanted^
( 57 )
falts, and refins of various kinds, by
the heat of the atmofphere. The
terms, evaporation, &c. as (imply
indicating a lofs of weight, may be
applied to both. Evaporation is not
folely effected by the mediation of
heats ftrong dry winds in cold frof-
ty weather, are often more powerful
agents in promoting the evaporation
of water and other fluids, than the
greateft heat of the fun in fummer.
The fuperficial parts of fluids are the
only ones which are evaporated ei-
ther by heat or air; and hence, in
fimilar circumftances, the quantity
evaporated, in any definite portion
of time, will be greater as the fur-
face of the fluid is greater. For this
reaf©B, the pans in which brine is
boiled for the making of fait, and
the pks, in which fea water is eva-
porated
( 5* )
porated by the fun and air for the
fame end, are ufually made very
lhallow, and of a large area ; and a
proper attention to this circumftance
might be ferviceable to fugar-ba-
kers, confeftipners, and other artifts
who are under the necefiity of eva-
porating large quantities of water.
However, as a fluid contained in a
deep veflel, when heated to a cer-
tain degree, retains its heat longer
than it would do, if it was fpread
over a fhallower veflel, and heated
to the fame degree ; it may become
a doubt whether the quantity eva-
porated in confcquence of its retain-
ing heat longer, may not be equal to
or exceed the quantity evaporated
from the fhallower veflel, in confe-
quence of its larger furface. Ic
might, perhaps, be an ufeful pro-
blem
( 59 )
blem to determine, by more accu-
rate experiments than any which
have been hitherto made, the length,
breadth, and depth of a vefTel which,
with the confumption of a definite
quantity of fuel, would evaporate
the greatefl poffible quantity of any
fluid in a certain time.
OF DISTILLATIONAND SUBLIMATION,
Though, in theprocefs of evapo-
ration, the volatile parts of bodies
are ufually difperfed in the air, and
the remaining ones only preferved,
yet it often becomes necefTary to
collect the volatile parts themfelves:
when this is the cafe, proper vefTels
are made ufe of for the purpofe, and
the operation, if the parts are fluid,
is called, d'iftillation, from their being
eolkdled drop by drop, ./?///#//';#. - If
the
C 60 )
the volatile parts when collected,
are dry and in a concrete form, the
procefs is called, Jublimationy from
the parts being driven upwards by
the force of the fire, and collected at
a diflance from the remaining parts.
The volatile parts thus collected,
may in general be called fublimates;
they are of different confiftencies,
fome being in hard mafles, others in
the form of a fine powder. Chemifts
have agreed to apply the name of
fublimatey to fuch as are in confiftent
maffes, the others, they call flowers:
thus we hear of corrofive Jul>limatey
and of fowers offulpbur. The foot
of a chimney is a matter fublimed
from the fuel, and it comes under
the denomination of flowers, or fub-
limate, according as it is of a pow-
dery or confident appearance. Du-
ring,
ring the fmelting of lead ore, that
impalpable fubftance which uTucs
out of the chimney of the furnace,
and falling upon the adjoining
grounds, renders the grafs- unwhole-
fome for cattle, may properly be
called the flowers of lead ore. This
diftindtion between diftillation, as
collecting the fluid, and fublimation,
as collecting the folid parts of bodies,
is not always fcrupuloufly adhered
to ; fmce the bell authors fpeak of the
diftillation of fulphur, and of other
bodies whofe volatile parts are dry.
The chemifts ufually diftinguifh
.diftillation into three kinds, accord-
ing to the different manners, in which
the diftilled vapour is collected. The
vapour in all cafes flies from the fire;
hence when the fire is placed above
the vefifel which contains the matter
to
to foe (Milled, the vapour in efcaping
from the fire, will defcend, and be-
ing col lefted in a proper veflfel, the
diflillation is faid to be made,/w de-
Jcenfumy bydefcent. When the fire is
placed under the veflel containing
matter to be diflilled, the vapour
will afcend, and the diftiilation is
called, per ajcenfum^ by afcent ; this
is the common manner of diftilling
low wines andfpirits. Befides thefe
two kinds of diftiilation, there is a
third, which ufually takes its deno-
mination from the form of the vef-
fel, in which the matter to be diftil-
led, is put. This vefTel is bent, and
hollow, fomewhat refembling in
ihape, a bullock's horn ; it is from
thence, called by the French, a cor-
:me-, more generally, from its curved
ihape, a retort. The lower and more
3
( 63 )
capacious part of the retort is called
its belly; this is fometlmes made al-
moft globular, that it may contain
the more; the tapering crooked part
is called its neck, and this part is
joined to the belly, with various de-
grees of obliquity, according to the
ufe to which the retort is defigned.
A large pear, with a long bent neck,
may give an idea of the fhape of a
retort, The matter to be diftilled,
be it liquid or folid, is put in at the
neck: it defcends into the belly of
the retort : the heat is applied to the
belly ; the vapours in flying from the
heat, ftrike againft the upper fide or
roof, as it is called, of the retort.;
finding no exit there, they are forced
out. laterally through the neck; the
neck of the retort is clofely joined to
another hollow velTel, which from
its
(•64 )
its office, in collecting the diftilled
vapour, is called the receiver or reci-
pient ; the diftillation is faid to be
made, per latus, by the fide, or per
wtortam, by the retort. The retorts
are made of various materials, as of
glafs, iron, earth, according to the
degree of heat to which they are to
be expofed.
It is not certainly known when,
or by whom, the art of diflilling was
firft found out, A diligent fearcher
into antiquity, informs us, " that
about the year 1150, the Moors of
Spain firft introduced the art of dif-
tillery into the weft of Europe, they
having learned it from the African
Moors, who had it from the Egyp-
tians ; but how long before die faid
African Moors had been in pofleflion
ef this curious art, does not clearly
appear,
( 6$ )
appear. Certain it is that this art
was not known to the ancient Greeks
and Romans, fince neither Pliny,
nor any other Latin or Greek author,
makes mention .of it,*.'*
To me it feems probable that the
art of fublimation was knov/n before
that of diftillation. The term alem-
bic or alamtiC) is compounded of the
Arabic particle al fine), and the
Greek word ambix, a kind of cup or
cover of a pot -, it is now ufed to de-
note the whole of a certain (Milling
apparatus; it formerly denoted only
one part of it, namely the head, or
that part in which the diftilled mat-
ter was collected. Diofcorides is
thought by Suidas, to have been
phyfician to the celebrated Queen
Cleo-
-' Anderfon on Comm. Vol. I. p, 83.
VOL. J. E
( 66 )
Cleopatra; he certainly knew the
manner of fubliming quickfilver
from its ore, and he calls that part
of the apparatus, in which the fub-
limed quickfilver was collected,
ambix f; the addition of a fpout or
beak to his ambix, would have fur-
nifhed him with a complete inftrn-
ment for diftilling, as well as fublim-
ing. But no one who confiders how
*ear the ancients were to the difco-
very of printing wiihout finding it
out, can be furprifed at their know-
ing fublimation, and at the fame time
being ignorant of diilillation -, for
that Diofcorides was ignorant of the
art of diftilling, may be reaibnably
conjectured, when we confider the
fad fhift he was put to in order to
collect an oil which arofefrom boil-
ing
•f L« v. c, i io«
C 67 )
ing pitch: he orders a clean fleece
of wool to be ftretched over the pot
in which the pitch was boiledj and
the oil to be pfefied out of the wool
as often as it became fufficiently wet
with it.
It mud be owned, that this argu-
ment is not intirely conclufive againft
the opinion of thofe who think that
the art of diftillatior -vas known to
the more ancient Greeks and Ro-
mans. For Diofcorides might have
had his reafons for making ufe of the
contrivance here mentioned, though
he had been acquainted with diftil-
lation* It feems mod natural to ex-
pect fome account of this procefs in
the writings of the phyficians Hip-
pocrates and Galen, had they been
-acquainted with it$ but there are no
pafiages in their works, from which
E 2
( 68 )
any certain conclufion can be drawn
relative to their knowledge of this
operation. Geber, the Arab, was
well acquainted with it, for he has
given us a chapter on the fubjecT:, in
which he lays down rules for diftil-
ling fer defc en/urn, and per afcenfumy
but he fays nothing of diftillation
per retortam. But diftillation was
known, to the Egyptians at lead,
fome centuries before the age of
Geber: for Zofimus of Panopolis
in Egypt, who lived in the fourth
century after Chrift, if not fooner,
has exhibited fome figures of a di-
flilling apparatus f . OF
f Thefe figures may<be feen in Borrichius*
Hermetis et ^.gyptiorum Sapientia, p. 156.
The word Cbemla firil occurs in the works of
this Zofimus. He fays, though one may
wonder whence he got his information, that
.it was in ufe before the Deluge, and that it
fignifies
C
OF DEPHLEGMATION, CONCENTRA-
TION, RECTIFICATION.
The word phlegm ufually denotes
the moft watery parts of bodies, and
when thefe parts are feparated, ei-
ther wholly, or in a great degree, ei-
ther by diftillation or fublimation,
the
lignifies fomething concealed. The Arabic
tongue, according to Bochart, furnifhes us
with the word Kemi fignifying concealment,
and thence he derives Chemia, rather than
from Cham the Hebrew root. Egypt is called
by Plutarch in Ofiridc^ Chemia, which Ortelius
expounds; for Chamia, from Cham the fon of
Noah. As the Arabians do not always copy
exaclly the proper names they borrow from
the Hebrew,- may it not be conjedtured, that
the Arabic Ifimi, fignifying concealment,
was introduced into that language, from the
fccret and hieroglyphic manner, in which the
priefls of Cham (Egypt) concealed their
knowledge of chemiftry and other arts ?
E 3
( 7° )
the bodies, be they folid or fluid, are
faid-to be dephlegmated. When the
watery parts of any compound fluid
are by any means taken away, the
remaining parts approach nearer to
each other, and may on that account
be faid to be concentrated; though
the term concentration is chiefly ap-
plied to the reparation of water from
acid liquors. It frequently happens
that the produces obtained by one
operation, are not fufficiently pure
and homogeneous, and that a fecond
or third diftillation or fublimation
becomes neceffary to exhibit them in
a proper form : this procefs of puri-
fying the fame body, how often fo-
ever it be repeated, is called reft$-
cation. Thus when we hear of an
oil, or volatile falt^ eight or ten times
rectified, we are to underfland that
C 71 )
it has been fo often rediflilled or re-
fublimed. If the impurity, to be
taken away, be a fimple phlegm,
it is obvious that the terms rectifi-
cation, concentration, and depleg-
mation, may be fynonymous ; and
indeed they are often ufed promif-
cuoufly. Thus weak vinous fpirits,
and weak vinegars are rectified, con-
centrated or dephlegmated by froft ;
for the water contained in thefe
fluids being frozen and taken away
in the form of infipid ice, the remain-
ing fluids become flronger.
OF THE DEGREES OF H£AT COMMONLY
USED IN CHEMISTRY.
From what has been faid relative
to the fixity and volatility of bodies,
it may readily be conceived, that the
operations of diftiliation, and fubli-
E 4 mation,.
( 7* )
mation, by which the volatile parts
of bodies are collected, will require
different degrees of heat, according
to the nature of the body whofe
parts are to be diflilled or fublimed.
It would be endlefs to enter into all
the fancies and contrivances of che-
mifls upon this fubjedb •, yet there
are four modes of applying heat,
which, though they are not fo well
defined that the degree of each can
be accurately afcertained, ought to
be particularly noticed, — the beat
of boiling water-, — a Jand heat ; — a
naked fire beat ; — and a folar heat.
Water, highly rectified fpirits of
wine, and other homogeneous fluids,
cannot be heated in open veflels, and
in agiven flare of the air, beyond a cer-
tain degree peculiar to each. As foon
as they fully boil, no continuance or
in-
( 73 )
increafe of fire can communicate to
them any increafe of heat; hence a
veflel, containing a body to be di-
Hilled, being expofed to the action of
boiling water, all the parts of the
body which are volatile, with the
degree of heat in which water boils,
will be elevated from the body *, and
may
* This obfervation is not, probably,
perfectly juft. — It is a very remarkable
phenomenon, that a veffel containing water
will never boil, how long foever it be ex-
pofed to the a&ion of boiling water. The
reader may convince himfelf of this by
an eafy experiment.. Fill a common bot-
tle with watert put the bottle thus filled
into a pan of water, fo that the mouth
of the bottle may be a little above the
water in the pan ; fet the pan on the fire,
and when the water in the pan boils in
the mod: violent manner, that in the bot-
tle will be obferved not to boil, and if
its heat be examined by a thermometer of
Fahrenheit's
( 74 )
may be collected in proper vefTels,
\vhilll the other parts, if the body
confifts of different principles, will
remain at the bottom of the veffel.
This heat of boiling water is one of
the mod definite degrees known in
chemiftrys there are many delicate
operations, efpecially on vegetables,
in which it would be improper to ufe
fo great a heat as that of boiling water;
but it is not necefTary to enlarge
upon
Fahrenheit's fcale, it will not be found to
amount to above 202 degrees, whilft that of
the boiling water in the pan is 212 degrees.
Hence it fiiould feem, that bodies, diftillcd in
vefTels expofed to the a&ion of boiling water,
do not experience the heat of boiling water,
This phenomenon is mentioned from Bar-
tholm's Acta Medica, in the Fhilof. Tranf.
for 1673, No. 97. — See alfo Profeflbr Braim's
Exper. Nov. Comm. Fetrop. Tom, XII. p».
289. — andKozier's Journ. 1773;
( 75 )
upon this obfervation in this place.
Boiling mercury, boiling lead, boil-
ing copper, would afford other defi-
nite degrees of heat; and boiling oil
might be very properly ufed as a
mean of diftilling bodies, notwith-
flanding that oil thickens in boiling,
and thereby becomes hotter as the
more fubtile parts are difperfed.
There are many bodies, and parts
of bodies, which cannot be rendered
volatile by the heat of boiling water j
thefe are ufually diflilled by iinmerf-
ing the vefTel containing them in
fand, and applying the fire fo as to
heat the fand; for the fand gradually
communicates its heat to the vefiel
which it touches : the fand is gene-
rally put into an iron pot; it is evi-
dent that the fire which is employ-
ed to heat the pot, may communi-
cate
cate any degree of heat to the fand,
from the fmalleft, to that which is
fufficient to melt the iron, fo that it
would no longer hold the fand. —
When the heat is communicated to
the vefTel, containing the body to be
diftilled, through any medium, as
that of boiling water, or hot fand,
the body is faid to be diftilled in a
water bath, or fand bath, the che-
mifts having agreed to call the me-
dium, ferving for the communica-
tion of heat to the diftilling or fub-
liming veilel, a baths and formerly
befides water and fand, they ufed
vapour, iron filings, woodafhes, &c.
for this purpofe.
When neither the heat of boiling
water, nor of ignited fand, is fuf-
ficient to feparate the volatile parts
of a body from the- remainder; the
vcfc
( 77 )
*veflel containing the body is ex-
ptifed to a naked fire ; that is, it is
furrounded with burning fuel, and
by a contrivance in the ftruclure of
the furnace, the flame of the fuel is
often made to reverberate upon it.
This degree of heat is alfo indefinite;
it may be augmented, by bellows and
other means, to fuch a pitch as to
melt the furnace containing the fuel,
or the veflel containing the body to
be diftilled. The degree of heat
•which may be excited in furnaces is
undoubtedly very great, yet it is far
inferior to that of the fun's rays
when collected into a focus by a
burning glafs or fpecuium: the force
of this folar heat cannot, perhaps,
be fubject to any other limit, except
what ariies from the difficulty of
forming large fpeculums.
Of
OF SOLUTION, SATURATION, AND
CRYSTALLIZATION.
When the parts of a folid body,
as common fait or fugar, are fo
united to a fluid, as water, that they
compofe with it an apparently ho-
mogeneous fluid, remain fufpended
in it, and do not deftroy its tranfpa-
rency, the folid body is faid to be
diffived in the fluid, the operation is
called/0/«/20tf ; the fluid, being look-
ed upon as the principal agent in
difTolving the body (though all ac-
tion is mutual and equal), is called
ihefolvent, or more commonly, ac-
cording to fome filly or indelicate
ideas of the alchemifts, the menftru-
%m'9 the compound refuhing from
the union of the fluid and the body,
is called ajolution of this or that
body,
3
( 79 )
body, in this or that menjlruum,
Thus we fpeak of a folution of
common fait or fugar in water, of
a folution of fulphur in oil of tur-
pentine, of camphor in fpirits of
wine, of filver in aqua fortis, and
fo on. The term folution is alfo
fometimes applied to the union of
two fluids ; thus the air is faid to be
difiblved in water, becaufe all na-
tural water contains air ; and water
is faid to be diffolved in air, becaufe
the raoft tranfparent air contains a
confiderable portion of water: thus
alfo various forts of oils are. faid to
be diffolved in fpirits of wine. And
laftly, folution is applied to the
union of two folid bodies : thus
glafs is a compounded body refult-
ing from the mutual folutron of an
eartn and a falc.
It
It may be worth while to explain, a
little more fully, the fir ft and moft
obvious notion of folution j that in
which a folid body is united to a fluid.
If you take an ounce of common fait,
and throw it into a quart of water, it
will fall to the bottom of the water,
as an ounce of fand or chalk would
do 5 but it will not, like them, (lay
there; in a very little time, efpeci-
ally if the water be flirred, the fak
will intirely difappear, it will be uni-
formly difperfed through the whole
body of the water, no one drop of
water will contain more particles of
fait than another, nor will any of
them contain fo much fait as it is
able to do. For if you add another
ounce of fait, that will alfo be dif-
folved, but not quite fo fpeedily as
the firitj and that will alfo be uni-
formly^
( 8: )
formly diffufed through the whole
body of the water, fo that each drop
of water will now contain twice as
much fait as it did before. This pow-
er which the water has of taking up
and keeping fufpended the particles
of fair, is not unlimited ; you may-
add fo much fa'lt to it, that it will not
difTolve one particle more, the wa-
ter in that (late is properly enough
faid to bzfaturated. All other men-
ftruums are likewife faid to be fatu-
rated, when they will not take up and
keep fnfpended any more of the bo-
dy diiTolved in them : thus a pint of
fpirits of wine will only take up a
definite portion of camphor -, a pint
of oil of turpentine will only keep
diflblved a definite portion of fill-*
phur; and a pint of aqua fortis will
be fofaturated with a definite portion
V«L. i. F cf
( 82 )
of filver, that it will have no fort
of aftion upon any additional quan-
tity which lhall be put into it.
We do not know either the fize
or the fhape of the particles of wa-
ter, nor whether they are contiguous
to each other, nor how they come to
attract the particles of fait more
flrongly than they attract each
other; but it is, notwithftanding, to
this prevalent attraction, that we at-
tribute the folution of the fait in wa-
ter, and of every other body in its
proper menftruum. We are certain
that every particle of water attracts
to itfelf and keeps fufpended a par-
ticle of fait, of a definite weight;
otherwife an equal number of thefe
particles, conftituting drops or par-
ticles of equal bulks, would not have
equal weights, nor contain equal
3 quan-
t 83 )
quantities of fait, which we are cer-
tain they do. Now if we fuppofe a
fingle particle of water to be evapo-
rated, or any how taken away from
a faturated folution of fait, then the
particle of fait which was kept fuf-
pendecl by the attraction of that par-
ticle of water, muft of neceflity have
a tendency to fall down to the bot-
tom; becaufe every other particle of
water, being fuppofed to have as
much fait united to it as it is able to
fuftain, can contribute nothing to its
fupportj and if inftead of one parti-
cle of water we fuppofe a thoufand,
or ten hundred thoufand to be eva'-
porated. then will a thoufand, or ten
hundred thoufand particles of fait
be left without any fubftance to fup-
port them ; and having no furround-
ing fluid to hinder their mutual at-
F 2 tractions
C 84 )
tractions from taking place, they
-will coalefce together upon the fur-
face of the folution from which the
water has been evaporated, and by
their union conftitute a faline pelli-
cle, which will be viflble to the na-
ked eye. This pellicle, as foon as
it becomes heavy enough to over-
come the tenacity of the fluid upon
which it floats, will by its gravity
defcend from the furface where it
was formed, ,to the bottom of the
veflcl containing the folution ; or,
meeting with afperities on the fides,
it may attach itfelf in part to them.
But the taking away a part of the
difTolving fluid is not the only mean
by which the particles of the dif-
folved body may be made to unite ;
there is another, and in many in-,
ftances, full as efficacious a one, the
taking
faking away a part not of the Tub*
{lance, but of the heat of the difTolv-
ing fluid. Thus if you put into a
quart of boiling water as much fait-
petre as it will diflblve, and filling a
bottle with the boiling folution, In-
flantly cork it up $ then you are fure
that no part of the water can efcape;
and if the diminution of the quan-
tity of a menftruum was the only
way by which the parts of the dif-
folved body could be made to unite,,
then would the particles of the dif-
folved fait petre, in this inftance, not
unite at all, iince there can be no di-
minution of the quantity of the dif-
folving water : you will, however,
on the contrary, obferve the parti-
cles of the fait coahfcing together,
as the folution grows cold, and
forming large and; regular cryflals.
F 7 —The-
( 86 )'
— The word cryftal is derived from?
the Greek words cryos, frofl, and
fallow to contract. The ancients fup-
pofed a particular mineral known
by the name of rock cryftal, to be
nothing but congealed water j this
mineral is of a determined angular
figure, and hence all falts and other
fubftances which from being dif-
folved in menftruums, or fufed in
fire, concrete into regular figures,
are faid to be cryftallized.
There are a great many circum-
flances relative to the manner in
which different falts cryftallize,
which cannot be infilled on in this
place; one thing deferves particu-
larly to be remarked, — that every
fait in cryftallizing, invariably af-
fumes its own peculiar form. You
snay diffolve common fait, or falt-
C 87 )
petrc, a thoufand times, and cryftaJ-
lize them as often by evaporating or
cooling the water in which they are
diiTolved, yet will you ftill find the
common fait will be confbantly cry-
frallized in the form of a cube, and
the faltpetre in the form of a prifm ;
and if you examine with a micro-
fcope fuch faline particles as are not
vifibkto the naked eye,.you will ob-
ferve thefe particles to be of the
fame fliape with the larger mafTes.
The definite figure appropriate to
every particular fpecies of fak, may
admit a little variety from the acci-
dental admixture of other bodies, or
from fome fingular circumftances at-
tending the evaporation and cryflal-
lization of the folution ; but thefe
varieties are foreign to the nature of"
she falr^and are not greater than what
F 4. attend
( 88 )
attend almoft every fpecies of vege-
tables, and even of animals, from
change of food and climate.
Here a large field of inquiry opens
to our view ; and though it be bet-
ter, as Seneca has it, de re tpfa qti<e-
rere quam mirari> yet all our attempts
to inveftigate the works of God, are
weak and ineffectual : we feel his in-
terference every where, but we can-
not apprehend the nature of his
agency any where. A blade of grafs
cannot fpring up, a drop of rain can-
not fall, a ray of light cannot be
emitted from the fun, nor a particle
of fait be united, with a never fail-
ing fymmetry, to its fellow, without
him : every fecondary caufe we dif-
cover, is but a new proof of the ne-
cefiity we are under of ultimately
recurring to him, as the one primary
caufc
caufe of every thing. Yet notwith-
flanding this our utter inability to
fearch far into the nature of things,
philofophical inquiries are by no
means without their ufe. He who
finds his endeavours to comprehend
the works of creation checked at
every turn -, who underftands that
every the minuteft part of this little
earth, which is itfelf nothing, as it
were, when compared with the infi-
nity of the divine works, is to him
one great miracle ; will not be over-
zealous in affirming that God can-
not interfere by his providence, in the
management of what he hath made,
or that he has interfered in this or
that particular way. In the confci-
ous abafement of his own intellect,
which philofophy will have taught
him, he will be cured of all attach-
ment
( 90 )
inent to fyftem, whether it be aTyf-
tern of bigotry or infidelity : he will
not be fond of anathematizing every
one who cannot think with him in
religious matters 3 nor on the other
hand will he contend that a revela-
tion from God muft be an impofli-
bility, from any abftract notions he
may have framed of the nature and
works of the Supreme Being. But
to return to our fubjecTr.
If what has been faid relative to
cryftallization, be not perfectly in-
telligible to the reader, I would ad-
vife him to make the following eafy
experiment, which will give him a
better notion of the matter than a
thoufand words. Into a bafon full
of boiling water, put as much falt-
petre as the water will take up; if
the faitpetre was purified^ the tranf-
parency
( 9' )
parency of the water will not be in-
jured, it will Hill appear to be air
homogeneous fluid : when the water
will take up no more faltpetre, then
he may conclude that it is faturated :
let it ftand without being flirred,
till it grows cold. As it cools, a great
many cryftals, all of the fame fhape,
may be feen (hooting out from the
fides and bottom of the bafon, and.
increafing in fize till the folution be-
comes quite cold. When no more
cryilals can be formed by that de-
gree of cold which prevails in the
apartment where the experiment is
made, pour the liquor from the folid
cryftals -, this liquor is flill faturated
with faltpetre, ; and in order to make
it part with more of its faltpetre?
fome of the water which keeps it dif*
folved mult be evaporated : upon the
taking
( 9* )
taking away a part of the water, a
correfpondent part of the faltpetre
lofes the power by which it is fuf-
pcnded, and ought, upon that pre-
fumption, inflantly to fall to the bot-
tom : yet it muft be remembered,
that the water, from its increafedheat
during the evaporation, is able to
fupport more faltpetre than if it was
cold ; and therefore the faltpetre will
not begin to cryftallize, notwith-
ilanding the lofs of part of its men-
ftruum, till the remainder begins to
cool. By repetition of this pro-
cefs of evaporation and cryftalliza-
tion, we may obtain all the faltpetre
which was at firft diffolved, as no
portion of it can be evaporated with
that degree of heat which is ufed
in evaporating the water.
OF
( 93 )
OF MIXTURE AND FILTRATION.
There is a difference between/0///-
lion and mixture fufficiently obvious,
though not always attended to. —
. Thus water which fprings from
chalk, has often, when the fprings
are low, a milky call arifing, from
fome very fine particles of chalk
which are mixed with it, but not dif-
Johed'm it; for perfect folution is al-
ways accompanied with tranfparen-
cy. Briftol and Matlock waters are
very tranfparent, though they con-
tain a large portion of earth ; but
the earth is in the flate of a fait,
and perfectly, difTolved in them.—
Turbid waters, turbid folutions of
falts and other liquors which con-
tain, mixed with their fubftance, any
heterogeneous matter, are "purified
to
< 94 )
to a certain degree by filtration*, t'hac
is, by being made to pafs through
certain fubftances, whofe pores are
large enough to give a pafTage to the
particles of water, and to the parti-
cles of any fait dilTolved in water, but
not to the earthy or oily fceculences
which may happen to be mixed with
it. The fubftances made ufe of are
called filters -, they are either fand, or
a porous kind of fione, thence called
a filtering ilone, or flannel, or linen,
-or leather, or brown paper into the
compofition of which no fize has
entered : this Jaft fubftance is gene-
rally ufed in fmall chemical experi-
ments ; it is made up into a conical
form, and placed in a funnel, or other
convenient inftrument to fnpport it.
Filters are ferviceable inftruments,
-not only for the purifying of liquors,
but
( 95 )
but for the feparating of any kind of
fait from a mixture of fait and earth,
and enabling us to afcertain the pro-
portion of fait and earth contained in
anypropofed fpecimen. Aninftancc
will illuftrate rny meaning. It is
commonly known, that wood allies,
fern aQies, and the afhes of moft ve-
getables, confift partly of a particular
kind of fait, partly of earth. Sup-
pofe it was required to determine the
proportion of fait and earth con-
tained in any fpecimen of afhes, the
procefs mud be conducted in the
following manner: — Take a pound
of the allies, previoufly well dried,
boil them in a quart of water, pour
the water and the afhes into a filter,
the water will pafs through the
filter, bringing with it the fait con-
tained in the afhes ; for water dif-
folves
( 96 )
folves all kinds of fait, and no kind
of earth : the earth therefore of the
afhes will be left in the filter : wafli
the earth remaining in the filter, by
pouring upon it hot water, till the
water in filtering through it comes
off wholly without tafte ; then eva-
porate all the water in .which the
allies were boiled, and with which
the earth in the filter was wafhed,
and when all the water is difiipated,
there will be left a greyifh kind of
fair, of a very pungent tafte. When
this fait has been dried as much as
the afhes were, it muft be weighed
whilft warm from the fire, and its
weight) noted ; then dry in the fame
manner the earth .remaining in the
filter; and the weight of the earth
thus dried, added to the weight of
-the fait, which has :ban extracted.,
( 97 >
will, when the experiment has been
properly made, amount to the
weight of the afhes employed in
making it.
OF THE ANALYSIS OF BODIES.
Moft of the bodies which we meet
with upon the furface of the earth or
below it, are compounded of hetero-
geneous principles -, thefe principles
muft, in many inftances, be feparated
from each other, before either the
nature of the body can be properly
tmderflood, or the principles them-
felves be applied to any ufeful pur-
pofe. Thus the juice muft be pref-
ffd from the earthy part of the grape,
the fugar cane, and the olive, before
we can obtain either wine, fugar, or
olive oil. The faline matter mint
be extracted from the earthy part of
VOL. i. G the
C 98 )
the alhes mentioned in the la ft ex-
periment, before it can in many cafes
become ufeful as a fait. Sulphur or
arfenick, or both, muft in many irt-
flances .be feparated from the ores
of metallic fubftances with fingular
care, before the metallic fubftances
themfelves can become articles of
commerce j or even before their ex-
iftence, as condiment parts of the
ores, can be made apparent. Many
bodies, without any afiiitance from
art, fpontaneoufly refolve themfelves
into diftincl: principles j thus blood,
by {landing, becomes feparated into
a watery fluid, and a red flefhy fub-
flan-ce ; milk refolves itfeif in like
manner into cream, into curd, and
into whey. The procefs by which
the heterogeneous parts of a com-
pound body are feparated from each
other,
( 99 )
other, whether it be carried on by
nature or art, may be called the
cnalyftS) rejolution, or decowpofition
of the body. Hum ,rbod 10 tdbin'j)iB
It frequently happens, that the
parts feparated by one analyfis, are
themfelves compounded bodies, and
capable of being refolved, by a fur-
ther procefs, into more fimple prin-
ciples. Ju-ft as in language, a fen-
tence may be refolved into words,
words into fyllables, and fyliables
into letters ; fo in thb decompofit'io-h
of natural bodies, we at lail arrive at
principles which do not admit any
further refolution or change. Thefe
fimple, unchangeable principles are
called jlemexfs ; and it may, from
what has been advanced, be readily
apprehended, that the fame fub-
ilance may be efteemed an element by
G 2 one
( loo )
one man, which is not fo efleemed
by another, according to the differ-
ence of their fkill exerted in the ana-
]yfis of Writes™ ™" 3Sib
OF CHEMICAL ELEMENTS.
By chemical elements, which are
the 1 aft produces of chemical analy-
iis, we are to underftand, not very
minute indivifible particles of mat-
ter, but the fimple homogeneal parts
of bodies which are not capable, as
far as our experience teaches us, of
any far ther refolution or divifion, ex-
cept in a mechanical fenfe, into flmi-
lar parts lefs and lefs without end, as
water into vapour more or lefs fub-
" tile and attenuated. Ariftotle and
his followers efleemed earth, air •, fire,
and water y to be elements, fimple and
uniform in their feveral kinds, effen-
tially
(
tially diftincl, and utterly incapable
of being converted into one another,
yet eafily uniting together, and by
their different arrangements, pro-
portions, and mixtures, compofing
every body in the univerfe. Many
modern chemifis have adopted this
idea j others have increafed the num-
ber of elements, by adding a faline
principle j others have contended,
that fome of thefe elements, air and
fire, for inftance,are themfelves com-
pound bodies ; and others, laftly, are
perfuaded, that there is only one
elementary homogeneal matter, and
that all the varieties of bodies, as
well as of what are commonly efteem-
ed elements, ought to be attributed
to the different magnitudes and
figures of the particles compofing
them ; and as the component parts
03 of
of water and air, or any other body*
are by no means fuppofed to be ele-
mentary particles of matter, but ta
be made up of different numbers of
elementary particles arranged indif-
ferent forms, it may be thought pro-
bable, that mechanical caufes may
cither diminilh or augment the num-
ber, or change the difpofition of the
particles, and thus effect the feveral
varieties obfervable in nature.
It would be improper in this place
to enlarge on a fubjec% concerning
which both ancient and modern phi-
lofophers have been fo much divided
in opinion : Their great diverfity of
fentiment may fugged a fufpicion,
that the full comprehension of it does
not fall within the reach of the hu-
man unckrftandlng. The following
obfervation may, perhaps, tend a lit-
tle
tie to iHuftrate this matter. Let
us fuppofe that this terraqueous
globe was not furrounded with any
air or atmofphere, and that by an
approach to the fun, or an increafe
of the fubterraneous fires, by fome
means or other it fhould become
expofed to a heat four times greater
than the medium heat of our
fummer, which we may reckon to
be about 60 degrees of Fahrenheit's
thermometer ; then would an atmo-
fphere be quickly formed around it :
ali the water upon its fur face, mole
of the juices of plants and animal?,
and a great variety of mineral par-
ticles, would be raifed up in vapours
and exhalations, and whilft the heat
continued would be kept fiifpeneled
Jn an elaftic (late, and conftitute an
•atmofphsre analogous, as it may rei-
c 4 fonably
( 104 )
fonably be imagined, to the chaotie
ftate of our prcfent atmofphere, only
differing from it in this; that it
would require a greater degree of
heat, in order to keep the particles *
of matter from coalefcing into one
heterogeneous mafs. Again, in the
prefent ftate of the atmofphere, fup^
pofe that a great degree of cold
iliould continue unabated for any
length of time ; all the water upon
the furface of the earth would be
changed into a folid tranfparent
ftone, which might be dug out of
its quarry, and employed in build-
ing as well as marble, or any other
fpecics of ftone ; all the particles of
air would be brought clofer toge-
ther ; fome of them which were the
lead elaftic, would be re-united : and
imagining the cold to be indefinite-
( I05 )
ly increafed, what reafon can there
be againft fuppofing that the whole
atmofphere would be reduced into a
folid flate, forming an heterogene-
•pus cruft upon the furface of the
earth: the thicknefs of this cruft,
luppofing it to be as denfe as mar-
ble, would be about four yards ? It
will eafily be underflood, that wa-
ter, and air, and earth, are, upon this
hypothecs, but variations of the
fame element introduced by heat.
That the atmofphere which fur-
rounds the earth, was originally
formed from the chaotic mafs, by
having the more fubtile parts of
which that mafs confided, elevated
and put into an elaftic (late by
means of heat, feems not altogether
improbable. We find the atmo-
fphere or firmament immediately
fuc-
fucceeding the formation of light j
now, if the effect of that light was
heat, be the form or matter of it
what you pleafe, then would fuch
particles of the fhapelefs jumble,
as were capable of being evaporated
with that degree of heat, be elevated
in an elaftic flate, and a divifion or
feparation would be made in the
midft of the great abyfs, between
the waters which were of a nature
fubtle enough to be converted by
that degree of heat into an elaftic
fluid, conftituting the firmament or
atmofphere, and the waters which
could not be evaporated in that de-
gree of heat, but ftill remained co-
vering the furface of the globe, be-
ing not collected into one place,
that the dry -land might appear, till
the third day. Thia notion of the
atmo-
atmofphere and its formation, feems
to be conformable enough to New-
ton's opinion, expreffed in his letter
to Mr. Boyle. "I conceive the con-
futed mafs of vapours, air, and ex-
halations, which we call the atmo-
fphere, to be nothing elfe but the
particles of all forts of bodies of
which the earth confifls, feparated
from one another, and kept at a di-
ftance by the faid principle*," — a
principle of repulfion.
*• Boyle's Life, prefixed to the fol. edit, of
hi* Works, p,. 7 1.
:3qq£ Jfigwn DfifiH
on eijdl
ESSAY
V
'
'
I
•
ESSAY III;
OF SALINE SUBSTANCBS,
IT may be expefted that this dif-
quifition fhould be commenced
by giving a rigid definition of the
term fait, or faline fubftance. But
the complex ideas of natural fub-
ftances are not fubjecl: to very de-
finite defcriptions. Nature, in her
feveral produ&ions, proceeds by
imperceptible gradations, feldom
leaving any decifive marks, by
which we can invariably difcrimi-
nate them into forts. The two moft
general id^as which appertain to the
word fait, ar e J 'aridity w\& filubility
in
( no )
in water, and fome add, want of in-
flammability in fire. Every fub-
ilance foluble in water, and affect-
ing the organ of tafte with a fenfa-
tion different from that excited by
its weight, may be called a fait: I
am fenfible that this defcription of
a fait cannot in all cafes be clofely
adhered to, without confounding
things fufrkiently diilincl:. Copper
by long maftication excites a nan-
feous tafte, and by lying long in
water it is in part dilTolved in it,
and yet we are not accuftomed to
clafs copper among faline fub-
ftances.
If any one fhould wifh to extend
the meaning of the term fait, by ap-
plying it to all bodies which have
regular figures, from fome obfcure
notion, that a faline principle is the
6 uni-
univerfal caufe of cryftallization,
then a variety of fpars and precious
flones, gla-'fles, and metallic fub-
flances, which are neither fapid nor
foluble in water, would be rightly
denominated falts $ and water itfclf,
when concreted into ice, would come
under the fame appellation. BuC
leaving this more enlarged fignifi-
cation of the word fait, to the con-
templation of thofe who are fludious
in the formation of fublime fy Items
of nature ; and confining ourfelves
to the more obvious properties of
fapidity and folubility in water as
charafteriftic of faline fubftances ;
we may proceed to obferve, that all
faks may be reduced to one or other
of the three following kinds ; they
are either,— acid Jails — alkaline Jalts
' — or neutral Jalts.
OF
{ 112 )
OF ACIDS.
The term acid explains itfelf by
its ordinary acceptation ; for though
there may be a great diverfity in the
tafles excited by different acid bo-
dies, both with refpeft to intenfenefs
and quality, yet no language has
furniihed diflin<fl names for this va-
riety. Sorrel, vinegar, cream of
tartar, lemons, tamarinds, and a
great many other bodies, are all faid
to "be acid when tafted ; and this
capacity of exciting an acid tafte,
is one charafteriftic of an acid fait.
All thofe bodies, with a very few
exceptions, which have an acid tafte,
have alfo when fufficiently puri-
fied, the property of changing the
blue colours of vegetables, as of
fyrop of violets into a red -, and
hence
( "3 )
hence this quality is reckoned ano-
ther character! flic of an acid fait.
The great divifion of all terref-
trial fubftances into minerals, vege-
tables, and animals, called the three
kingdoms of nature, has fuggeited
to chemifls a divifion of acids into
mineral, vegetable, and animal acids,
•according to the nature of the fub-
jecl from which they are produced.
The mineral acids may be copiouf-
Jy feparated, by diftillation, from
vitriol, nitre, and fea fait ; and in
-reference to thefe fubftances, they
are ufually called the vitriolic add,
the nitrous acid^ and -the marine acid.
' — The vegetable acids are either
native, fuch as exifl in four fruits
:and plants; or .factitious, fuch as
•vinegar and tartar* which are pro-
duced by fermentation. To the
VOL. i. H clafs
( "4 )
clafs alfo of factitious vegetable
acids, may be referred all the aeids
fcparable from vegetable matter by
diftillation { thefe generally retain^
ing a burnt fmell, are called em-
fyreumatic acids : they have not hi-
therto been fo fully examined as to
be clafled into different fpecies.
Animal acids are fuch as may be
feparated from various parts of ani-
mals by diftillation ; or they are fuch
as bees, ants, and fome other infects,
contain in proper vefTels ready pre-
pared, and which they eject in fling-
ing-
OF ALKALIES.
The term alkali is compounded of
the Arabic particle al (the) and kali>
the Arabic name of a maritime plant
called by us glafiwort, or marjh fam-
phire. Glaflwort is diftinguifhed
by
C "5 )
by botanifts into the greater or
feiTer jointed glaffwort, fnail-feeded
glaffworr, prickly glafTwort, &c. all
of which are called kali ; and from
the allies of them ally when tho-
roughly calcined, there may be
wafhed out a fait, which is called an
alkali, or an alkaline fait: If any
one fhould think that the word kali
is derived from an Hebrew root of
nearly the fame found, fignifying to
burn ; then he will conclude, that
alkali originally had reference not
to the name of any particular fpe-
cies of plants, but to the manner in
which a fait might be procured
from the afhes of burnt vegetables
in general; and that in procefs of
time a certain kind of plants came
to be called kali> from its afhes
abounding more, than thofe of any
H 2 other
C "6 )
other plant, with fait;
or foude, from being the common
name for this very fait, which is fe-
parated from kali, has become the
French name for the plant itfelf *.
Kali is not the only maritime
plant which yields an alkaline fait.
On the coaft of Spain, about Ali-
cant and Carthagena, and, indeed,
in many other countries bordering
on the Mediterranean, the farmers
fow their lands with the feeds of dif-
ferent forts of maritime plants,
which they pluck up at the proper
feafon, dry in the fun as we dry hay,
and burn to afhes. About Cartha-
gena
* Kali herbam in cinerem verfam So Jam
appellat vulgus. Baptif. Porta Mag. Nat.
L. vi. C. i. He defcribes the method of
extracting the fait out of the allies, and fays
that out of five pounds of the afhes they got
one of fait.
2
( "7 )
gena they principally cultivate four
forts of plants, barilla, gazul or algd-
zul}foza> and falicornia.- The barilla
yields the purefl fixed alkali; each
root of this plant fends out a great
many ftalks refembling famphire,
and rifing to about the height of
four inches. The ground is much
exhaufled by the crop, it lies fallow
every other year, and each acre pro-
duces about a ton of barilla*. Whe-
ther any of our fait marfhes could
be advantageoufly employed in this
kind of culture, may deferve the fe^
rious confiderauon of thofe to whom
they belong; certain it is, that plants
which would yield this alkali, grow
fpontaneoufly upon feveral of them,
.On the Orkney and Sciily ifles,
and on moft parts of the Britifh,
H 3 coaft>
* Swinburne's Trav, through
coaft, great quantities of bladder
fucus, or fea oak *, under the name
of fea wrack, are annually burned in
order to obtain an alkaline fair. The
plants are cut from the rocks on
which they grow, or gathered from
the beach on which they are thrown
by the tide; and being fufficiently
dried by the heat of the fun in the
fummer feafon, they are fet on fire*
the fire place is a hole in the ground $
the afties, to which the plants are re-
duced, are melted by the violence of
the fire; the melted mafs is kept in
a ftate of fufion for three or four
hours, it is then fuffered to cool, and
when it is fet, they take it out of the
hole in which the plants were burn-
ed, and the operation is recom-
menced. The folid mafs procured
from
* Fucus veficulofus, Linnaei.
( "9 )
from the melting of the afhes of fea
wrack, is an article of great ufe in
the making of glafs and foap, and is
known in commerce under the name
of ketp, or kelp afhes. From kelp
allies may be extracted a fait, the
fame in every refpect with that which
may be procured from the afhes of
kali or glafTwort. The following
experiment was made in order to af-
certain the quantity of faline matter
contained in Britifh kelp.
Thirty ounces of kelp from the
Orknies, which had been previously
pounded into a fine powder, and in
that (late well dried upon a hot iron,
were boiled in various portions of
water, till all the faline matter was
extracted from the afhes ; the water
containing all the faline matter of
the kelp was then evaporated with a
H 4 gentle
gentle heat, and the fait which re-
mained after the water was all eva-
porated, was further dried, as the
kelp had been, upon a hot iron. The
faline matter in that dry ftate weigh-
ed 19 ounces. The earth remaining
after the extraction of the faline
matter being carefully collected and
thoroughly dried upon a hot iron3
it weighed exactly in that ftate n
ounces. This experiment was re-
peated with the fame fuccefs.
There is a much greater quantity
of faline matter contained in SpanifH
barilla than in Englifh kelp, as may
be inferred from the following expe-
riment. Spanifh barilla, as well as
Englifh kelp, is mixed with feveral
pieces of black matter -3 this matter
confifts of pieces of the plants which
have been reduced to charcoal, but
not
not to afties, during the combuftionr
of the plants'. I pounded into a fine
powder a quantity of barilla; the
powder had a greyifh caft from the
charcoal it contained ; it was dried
upon a hot iron, and it loft by that
operation one fourteenth of its
weight. I took 30 ounces of this
dried barilla, and proceeding as in
the analyfis of kelp afhes, I obtain-
ed 22 ounces of faline matter. It
appears from hence, that there is
three hundred weight more of faline
matter in a ton and an half of barilla,
than of kelp afhes.
It is very probable, that ke] p. afhes
prepared in different countries, con-
tain the earthy and faline parts In
proportions different from thofe here
afcertained; yet it is worthy remark-
ing, that the analyfis here given coin-
( 122 )
cidcs, as to the earthy part> with the
experiments of one author, and as to
the faline part, with the experiments
of another. From 28 drachms of
kelp afhes, Dr. Home obtained 10
drachms of earth ; now the propor-
tion of 30 to IT 3 is nearly the fame
with that of 28 to 10*. — M. Cadet
obtained 6 pounds 3 ounces and
an half of faline matter from 10
pounds of kelp afhes; if he had
obtained one half ounce more, the
proportion of faline matter pro-
cured from the kelp he examined*
would have been almoft exactly
the fame with that procured from
the Orkney kelp which I exa-
mined f. I was not aware of
the
* See his very ingenious Effay on Bleach-
ing, p. 151.
f Hift. de 1'Acad, des Sciences a Par,
Ann. 1/67, p. 488.
the experiments here referred to7
when I undertook to afcertain the
refpedtive quantities of earth and
faline matter contained in kelp aflies,
and for that reafon the coincidence
may be the better relied on.
The reader may wonder, why, in
fpeaking of the fait contained in
kelp, I have called it by the general
name, faline matter, in the very place
where I was confidering it as a parti-
cular kind of fait, as an alkali : this
was not done without reafon ; for not
only kelp aflies, but the alhes of kali,
barilla, and moft maritime plants,
befides an alkaline fait, contain a por-
tion of common fait, and of fome
other kinds of fait, which it is not
neceflary here to enumerate. Thefe
foreign falts injure very much the
purity of the alkali, for the obtain-
ing
C
itig of .which the plants are burned £:
and the Britifh kelp alhes abound
with them fo much, thar from fomer
trials I have made I fhould conclude,
that the 19 ounces of faline matter,
which I had extracted from 30 ounces
of kelp, did not contain above five
ounces of pure mineral alkali free
from water. The exprefilon, free
from water, requires an explanation*
The 19 ounces then of faline mat-
ter obtained from 30 ounces of kelp,
weredifiblved in water, and from the
Solution, when evaporated and cry-
ftallized, I obtained 12 ounces of al-
kaline fait in very fine tranfparent
cryftals. Since all attraction is mu-
tual, it may readily be understood,
that as the particles of water attract
thofe of the alkaline fait, and retain
them in folution, fo the particles o£
the
( "5 )
alkaline fait will attraft thofe of
the water, and retain them in cry-
ilallization. The water thus attradt-
-ed by the particles of a fait during
its cryftallization, is ufually denomi-
•nated the water of cryftallizatwn.
This water of cryftallization is
^contained in different quantities in
.different falts, and it adheres to them
with different degrees of force;
though it is eafily feparated from
mod of them, the moderate heat of
the atmofphere being fufncient to
evaporate it from many. When this
water of cryftallization is evaporated
from any fair, the figure of the cry-
ftals is deftroyed; the fait from being
afolid tranfparent fubftance becomes
an opake powder. But though a
fait, in lofing its water of cryftalliza-
tion, lofes its cryftalline form, it does
not
•not thereby lofe part of its faline
quality ; for the water which is fcpa-
rated from it is pure water j and the
fait, by being redifiblved in water
and recryilallized, will not only re-
gain its former figure, but the whole
of its weight.
This obfervation refpecling the
water of cryftaiiization is not with-
out its ufe, either in medicine or
trade. The fait known in medicine
tinder the name of Glauber's fait,
is one of thofe which contains near
half its weight of water, wholly un-
efiential to it as a fait: hence an
ounce of Glauber's fait, in tranfpa-
rent cryftals, has not more ftrength
as a medicine, than half an ounce of
the lame fait when reduced to a
powder, by having its water of cry-
ftaiiization evaporated. The twelve
ounces
( '27 )
ounces of alkaline fait in queflion
were expofed to a very gentle heat
(they would have been melted by a
ftrong one) till they were reduced
to a fine powder: this powder was
dried on a hot iron, and in that ftat$
it weighed not quite five ounces; fo
that twelve tons of alkaline fait in
cry dais, is not worth more than five
tons of the fame fait, when freed from
its water of crystallization. Kelp
afhes appear, from thefe experi-
ments., not to contain above five tons
of the alkaline fait here fpoken of in.
thirty tons of the afhes.
I took the 22 ounces of faline mat-
ter which i had procured from 30
ounces of dried barilla, and diflblving
them in water obtained 36 ounces of
fine cryftals of alkali, and about 3
ounces of a fait which would not cry-
ftallize,
C
ftallize, and which was in part fea
fait. It appears from this experi-
ment, compared with the preceding,
that the fait procurable from barilla,
contains a far greater proportion of
pure alkali, than that from kelp
does; and hence barilla is preferable
to kelp, not only from its containing
more faline matter in a definite
weight, but from that faline matter
being of purer quality. The cry-
ftalline fait thus obtained, being ex-
pofed to the fire, was quickly melted,
end when all the water which had en-
tered into the compofition of the cry-
#als had been evaporated, the fait
•weighed 21.1 ounces, half an ounce
having been loft by the operation.
The alkaline fait contained in the
-afhes of maritime plants, when ex-
.pofed to the heat of a glafs-houfe
furnace,
( '29 )
furnace, lofes confiderably of its
weight, but in moderate fires it lofes
nothing; hence this fait is called a
fixed alkali. A pound of common
fait contains about half a pound of
this fixed alkali. Common fait is
reckoned a mineral, there being large
mines of it in mod parts of the
world. This fixed al kal 5, which con-
ilitutes near half the weight of com-
mon fait, and from the decompofi-
tion of which it is moft probably
produced, is therefore often called
the mineral, fojfite, or marine fixed al-
kali. It is entitled alfo to the name
of the mineral fixed alkali, from its
being met with in fome mineral wa-
ters, and from its being found either
ready formed upon the furface of the
earth, or dug out of certain lakes,
which are dried up in the fummer, in
-VOL. i. I
Egypt, and other parts of the Earl,
It is there called natron, and is fup-
pofed to be the nitre fpoken of by-
Solomon, when he compares the
effect which unfeafonable mirth has
upon a man in affliction, to the action
of vinegar upon nitre ; * " as vine-
gar upon nitre, fo is he that fingeth
fongs to a heavy heart:" for vinegar
has no effect upon what we call nitre;
but upon the alkali in queftion it
has a great effect, making it rife up
in bubbles with much effervefcence.
This alkali has been met with alfo on
the Pic of Teneriffe and in Barbary,
Ib that it is upon many accounts pro-
perly enough denominated the mine-
ral fixed alkali.
The alhes of rnoft other vegeta-
bles, as well as thofe of maritime
plants, yield a fait which has many
pro-
* Prov. xxv. so*
properties in common with the mi-
neral fixed alkali ; but not having all
the properties of that fait, it has, for
the fake of perfpicuity, been called
the vegetable fixed alkali. Both the
mineral and the vegetable fixed al-
kali are prepared by boiling the
allies, to extract the fait from the
earth 5 the water containing the fait
in folution, is then evaporated fo as
to leave the fait dry. From this
manner of preparing them, thefe falts
have been often called lixivial falts,
lix and lixivium both fignifying a ley
made with allies. The operation of
evaporating the water is performed
in large iron or copper pots ; and.
from this circumflance thefe alkaline
falts, efpeci-ally the vegetable fixed
alkali, have corne under the name
of frot-ejb.
1 2 -Great
( '3* )
Great piles of wood are, in many
countries, burnt for the exprefs pur-
pofe of obtaining pot-afh. From the
following experiments, fome notion
may be formed of the large quanti-
ties of wood which mud be burned,
in order to obtain even a fmall por-
tion of pot-afh.
I defired a friend in Eflfcx, who
had plenty of dry oak billets, to af-
certain the quantity of allies which a
certain weight of the wood would
yield. He made the experiment with
every poflible precaution, and from
1 06 pounds, avoirdupois weight,
of dry peeled oak, he obtained 19
Qunces of allies. I treated thefe aihes
after the fame manner in which! had
endeavoured to afcertain the propor-
tion of earth and faline matter in
barilla, and kelp afhes ; and from the
( '33 )
19 ounces obtained rather more
than one ounce and a quarter of fa-
line matter. From feveral repeti-
tions of the experiment with alhes
of the fame kind it may be con-
cluded that 15 ounces of thefe alhes
contained 14 ounces of earth, not
foluble in water, and i ounce of
faline matter : from this proportion
it rnayeafijy be collected, that above
1300 tons of dry oak, and probably
above 1800 tons of green oak, muft
be burned in order to obtain one
ton of pot-afh.
The makers of pot-afli generally
buy the wood allies by the bulhel,
and fell the pot-afh by the ton ; but
as the alhes of different woods, and
indeed of different parts of the fame
wood, probably contain very diffe-
rentportions of faline matter 3 it can-
1 3 noc
( '34 )
not be expected that we fhould have
any very uniform accounts of the
number of bulhels of alhes requifite
to make a ton of pot-afh. Some
dealers in this article are of opinion^
that a ton of pot-afh may be pro-
cured from 400 bufhels of afhes s
others, from 450 j others, from 560
of the beft aihes ; and others, laftly,
from 700 bufhels, at a medium, of
good and bad afhes*. I find that a
bufhel of the dry afhes which are
fold by the country people who burn
wood to our foap- makers in Gam-
bridge, weighs at a medium 58
pounds: hence, fuppofing every 15
pounds of fuch afhes to contain i
pound of faline matter, it will fol-
low, that 580 bufhels of fuch afhes
would
* Lewis's Experiments on American Pot-
ato, p. 6.
( '35 )
would give i ton of faline matter.
This correfpondence with the ac-
counts given by the pot-afti makers,
confirms the analyfis of the oak
afhes before mentioned.
Under the direction and patronage
of the Society for the Encourage-
ment of Arts, Manufactures, and
Commerce, large quantities of pot-
afh have been made in America fince
the year 1763 ; and it would be a
great faving to the nation, if it
could be made in fufficient quanti-
ties in any part of the dominions
of Great Britain, fince we are reck-
oned to pay to Ruflk, and other fo-
reign ffcates, not lefs than one hun-
dred and fifty thoufand pounds a-
year for pot-afh *. We have inex-
hauftible
* Doffie's Mem. of Agriculr Vol. I. p, 248,
14
( 136 )
hauflible mines of rock fait in this
country, which the proprietors can
afford at lofhillings a ton. A ton of
rock fait, as has been before obferv-
cd of common fait, contains about
half a ton of mineral alkali, which
is for moft purpofes far preferable
to pot-afli. If a method could be
contrived of extracting this alkaline
part from rock fait, it would be a
moft ferviceable difcovery. To
thofe who have leifure to attempt it,
I would give the following hint —
Whether the alkaline part of rock
fait may not be obtained by cal-
cining it in conjunction with char-
coal in open fires? My reafon for this
conjecture is founded on the fol-
lowing experiment : Upon burning
fea wrack to a black coal, and
flopping the procefs at that point,
1 have
C 137 )
I have obtained great plenty erf
common fait, but no mineral alkali
from the black afhes; though we
are certain, that when the black
afhes are thoroughly calcined, or
reduced to white afh.es, mineral al-
kali may be obtained from them.
This makes it probable, that the
common fait contained in the black
afhes of fea wrack, is decompofed,
and changed into a mineral alkali,
during the burning of the black
afhes. There are reafons to fuppofe
that the cinder of pit-coal would
anfwer the purpofe better than char-
coal. But to return.
Tartar is a vegetable production,
which forms itfelf on the fides of
cafks in which new wine is put -, it is
of a folid confiftency, and is thence
called by the Germans, wine-ftone
(wyne-
( 13* )
(wyne-ffein) : this fubftance, when
burned to afhes, yields a very pure
vegetable fixed alkali, called Jalt
tf tartar.
The reader is defired to diflin^
guifh between cream of tartar and
Jalt of tartar ; they are both falts,
but not of the fame clafs. Cream
of tartar is an acid, and is prepared
from tartar by diffolving it in water,
and cryftallizing the folution. Sale
of tartar is an alkali > and is prepared
from tartar by burning it, the acid
being probably changed into an al-
kali by the fire.
Salt of tartar, as well as all other
vegetable fixed alkalies when pure
(for when purified they are all the
fame), attracts very ftrongly the hu-
midity of the air, and thereby melts
as it were into a liquor, \vhich from
its
Its being procured in this fmgular
way, and from its having alfo an
unctuous appearance, though ithas no
other property of an oil, has been
called Oil of tartar fer deliquium. If
you fpread a little fait of tartar, or
even common pot-afn on a plate, and
expofe it to the air in a cellar or
other moifl place for a few days, you
will fee the whole of it almoft melt-
ed away into a thick tranfparent li-
quor, weighing near four times as
much as the weight of the fait you
expofed. The mineral fixed alkali,,
expofed in the fame way, will not be
changed into- a fluid ; and this is one
mark by which the mineral and ve-
getable fixed alkalies may be diilin-
guiflied from each other. Both of
thefe fixed alkalies change the blue
colour of fyrop of violets into a green*
and
C 140 )
and by this property they are diftin-
guilhable from acids, which give a
red colour, as well as by their tafte,
which is caufcic and fiery > every way
very different from a four tafte. They
bubble up alfo or effervefce when
mixed with acids, as may be feen by
mixing lemon-juice and fait of tar-
tar together. This effervescence pro-
ceeds from the difcharge of an elaf-
tic fluid, called fixed air ^ but it can-
not be faid to be characterise of al-
kalies; fince chalk, 'marble, lime-
ilone,and other earths and ftones noc
foluble in water, contain a large por-
tion of fixed airy and, when mixed
with acids, effervefce as much as
fixed alkalies. From this property,
thefe earthy and (tony fubftances
have, in many fyftems of mineralo-
gy, been called alkaline earths and
Hones. Befides
Befides the fixed alkaline falts
feparable from the afhes of mari-
time plants, and other vegetable
fubftances, there is another fpecies
of fait feparable chiefly from ani-
mal fubftances, as from urine,
horns, bones, &c. by diftillation.
This fait effervefces with acids, and
gives a green colour to vegetable
blues, and it is from hence called
an alkali -, but being eafily difli-
pated in a fmall degree of hear, it
is called a volatile alkali. By this
great volatility it is fufficiently dif-
tinguifhed from the two fixed al-
kalies, as well as by the pungency
of its fmellj fixed alkalies, when
pure, having no fmell.
OP
C 142 )
OF NEUTRAL SALTS.
Neutral falts are diftinguifhed
both from acids and alkalies by
their tafte, which is neither four
nor cauftic, by their not effervef-
cing with acids, by their not pro-
ducing any change in the colour of
fyrop of violets. Of this kind arc
common fait, Glauber's fait, fait-
petre, and a great variety of others.
Any acid, when united with any al-
kali in fuch proportion that the
compound does not poflefs any of
the character i flic properties of ei-
ther of its component parts, is a
neutral fait. The term neutral was
firit applied to a fait formed by an
union of an acid and an alkali ; but
it has now a more extenfive fignifi-
cation, denoting the fait formed by
2 the
( 143 )
the union of an acid with any alkali,
-earth, or metallic fubftance. The
fubftance with which the acid unites
itfelf in the formation of a neutral
fait, is often called the bafis of that
fait.
The following tables of falts will
help to fix in the reader's mind the
general divifion of faline fubftances,
efpecially if he will be at the trou-
ble to familiarize himfelf to the
names, by procuring from his drug-
gift fpecimens of the feveral kinds.
A TABLE
( 144 )
A TABLE OF SALTS IN GENERAL.
SALTS.
Neiltrali Alkaline
Acid
p I | 8.R-S1
j
A Table of neutral Salts, with Alkaline Bafes.
ACID.
S.t?
3. Cu g
tf.S.S
Ben] am
bedt.
3 >
8 8."
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P S
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3 «
fD CD
£3 O.
VOL. I
S S
3 >
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K
( 14* )
. It may not be improper, in this
place, to mention two propofitions
much infifted on by chemical writers
of the greateft eminence, but which
appear to be founded rather on pro-
bable conjecture than certain experi-
ment. The firft is, that the vitri-
olic acid is the only faline principle
in nature, all other acids, and alkalies
being nothing but combinations of
this univerfal acid with earth, air,
oil, and water, in different propor-
tions. The fecond is, that the vi-
triolic acid itfelf is a compound
bqdy, formed from an intimate union
of earth and water. The pofllbility
of the truth of the firfl propofition,
which aflerts, that one fubftance
may be fo combined with feveral
others as to conftitute a great variety
of different compounds, may be il-
luftrated
luftrated from what we know of
water; which is the chief conftitu-
cnt part of bodies in appearance
very different from each other, as
of blood, urine, milk, wine, wood,
coal, &c. yet the marine acid feems
to be as abundantly diffufed over
the earth as the vitriolic; and can-
not, I think, be faid to be derived
from it. As to the fecond propofi-
tion, though we fhould grant that
nothing but earth and water can be
procured from the analyfis of any
fait (which, confidering the lofs
fuftained almoft in every analyfis
from the efcape of fome elaftic fluid
which cannot be condenfed, cannot
readily be admitted) ; yet as no one
could ever form a faline fubftance
by uniting earth and water together,
we may fairly doubt concerning its
K 2 truth :
( 14* )
truth : this doubt, however, is not to
be uriderftood as a denial. The fum
of the matter is this : earth and wa-
ter cannot be formed by us into fa-
line fubftances: nature may have
different modes of combining them,
fo as to produce the effect; or na-
ture may* in producing the effecl,
make ufe of a third or a fourth prin-
ciple. It mud be left to future ex-
perience to fimplify our knowledge
concerning faline fubflances, as well
as concerning thofe fluids which pro-
duce magnetifm and electricity, and
all the various phenomena attending
mineral exhalations.
ESSAY
ESSAY IV.
OF FIRE, SULPHUR, AND PHLOGISTON.
FIRE is fo fubtile an agent in
nature, that we can reafon' lit-
tle concerning it, except from ex-
periment ; and we are even at a lofs
from thence to determine, in many
cafes, either its abibiute quantity
or real prefencejp'/lf, with the gene-
rality of philofophers, we afllime
heat as its character! flic property*
and define fire to be that which
warms or heats bodies, we cannot
avoid feeing at once, the ambiguity
of this criterion: it is as precarious
as the perceptions of different men
K i at
( '50 )
at the fame time, or of the fame
man at different times, in fummer
and in winter, in a fever and in
health. 2.The light of the moon,
•when collected into the focus of a
large burning- glafs, is found to] be
about one thoufand times lefs denfe
than the direct rays of the fun:
hence it is, that it excites no mo-
tion in the mercury of the mod
fenfible thermometer. But from the
brightnefs of the image in the focus,
as well as from the luminous ap-
pearance of rotten wood, putrid fifh,
and other phofphorefcent bodies,
fome philofophers have inferred,
that wherever there is light there is
fire: but as the converfe of this pro-
pofition is not true, fince fire often
exifts in large quantities, as in boil-
ing fluids, in metals moderately
heated,
heated, &c. without light; this can-
not be a diftincmifhing mark of the
prefence of fireWThe dilatation which
fire occafions in all bodies, whether
folid or fluid, hard or foft, light or
heavy, may be efteemed the mod
certain proof of its prefence and
agency. This property ferves admi-
rably to mark its degrees and mi-
nute variations within certain li-
mits, but not to afcertain either its
prefence or its quantity in extreme
cafes, unlefs we know the real mag-
nitudes of bodies totally deflitute
of it. However, admitting this
phenomenon as the mo ft certain in-
dication of the exiflence of fire, it
may be accounted for in the follow-
ing manner.
From the 1 4th fe<5bion of Sir Ifaec
Newton's Principia* -we learn, that
K 4 the
the motions of fmall bodies, when
attracted perpendicularly towards-
any furface, according to any law,
are fimilar to the motions of the
rays of irght, with refpect to the
fundamental properties of Inflec-
tion, Reflection, and Refraction:
from hence chiefly, as well as from
other arguments, we infer, that rays
of light are fmall corpufcles, emit-
ted from fhining bodies, and moving
with uniform velocities in uniform
mediums; but with variable velo-
cities in mediums of variable den-
iities. This being admitted, it will
follow, that in whatever quantity
the rays of light are made to move
in a medium of an uniform denfity,
they will not agitate the particles,
or produce any augmentation of
bulk in that medium. If the atmo-
. . fphere
( 153 )
iphere was reduced to a medium of
an uniform denfiey, furrounding the
earth every where to the height of
five miles, it would be expanded
in bulk, or warmed only at its out-
ward and inward furface. The fun's
rays, by coming out of a vacuum
into a denfer medium, would be
attracted by the particles compofing
that medium j and, fince all attrac-
tion is mutual, they would excite a
motion, an expanfion, an heat, at
the outward furface where they en-
tered : from thence they would pro-
ceed uniformly, without producing
any effect, till they came to the in-
ward furfice of the atmofphere con-
tiguous to the furface of the earth,
where they would undergo another
acceleration of velocity, and would
excite another degree of motion,
another
( '54 >
another degree of expanfion or heat.
Such an atmofphere would be the
coldeft in the middle, the heat de-
creafmg from each furface. We may,
perhaps, from what has been faid,
conceive, in fome meafure, how
bodies are expanded, heated, and
volatilized, by the agency of the
particles of light. Thefe particles
act upon the minute conftituent
parts of bodies, not by impact, but
at fome indefinitely fmall diftancej
they attract, and are attracted ; and
in being reflected, or refracted, they
excite a vibratory motion in the
component particles. This motion
increafes the diftance between the
particles; an increafe of the diftance
between the conftituent parts of
&ny body, is an augmentation of
bulk, an expanfion in every dimen-
fion,
( 155 )
fion, — the moft certain chara&eriftic
of fire. This expanfion, which is
the beginning of a difunion of the
parts being increafed by the in-
creaiing magnitude of the vibra-
tions proceeding from the continu-
ed agency of the light, it may eafily
be apprehended, that the particles
will at length vibrate beyond their
fphere of mutual attraction, and
thus the texture of the body will
be altered or deflroyed : from folid
it may become fluid, as in melted
gold; or from being fluid, it may
be difperfed in vapour, as in boiling
water.
"According to this theory, we muft
infer, that the conftituent parts of
all bodies are in perpetual motion.
The temperature of the atmofphere
is different in different latitudes, and
it
it changes, almoft every inftant, m
the fame. The temperature of bodies
is ever proportionable to that of the
furrounding atmofphere, and from
thence it rnufl be perpetually vary-
ing. The bulk of every body is pro-
portionable to its temperature, and
muft therefore be fubjecl: to a per-
petual viciffitude. Now 'the body
will be in an expanded, in the next
inftanr, its heat happening to be
diminifhed, it will be in a contract-
ed flate; which variation of dimen-
fions cannot be effected without a
perpetual vibratory motion of its
conftitueqt parts.
It being eftablifhed then, that the
rays of the fun, even in their moffi
cbnden.fed ftatc, as in the focus of a
burning fpeculum, do not otherwife
produce heat than as they excite a
. '
motion
( '57 )
motion more or lefs violent amongfl
the conftituent parts of bodies; and
the effeifls of culinary fire, of that
produced by fridtion, or by the im-
pa& of hard bodies, being fimilar
to thofe produced by the agency of
the fun's light, it may be conjec-
tured, that they are produced after
a fimilar manner; and that fire is
nothing diftindt from the parts of
bodies put into motion by various
caufes, as the impulfe of light, fric-
tion, percufiion, putrefaction, attrac-
tion of cohefion, &c. and confe-
•quently that it may be mechanically
produced, altered, or deflroyed in
all bodies, with greater or lefs faci-
lity, according as the parts of the
•body are more or lefs difpofed for
motion.
f This conclufion feems to be con-
foaant
( '58 )
fonant with the principles of the re.-
ceived philofophy. Newton in his
5th quaere annexed to his Optics,
afks, Do not bodies and light aft
mutually upon one another? that
is to fay, bodies upon light in emit-
ing, reflecting, refracting and in-
flecting it; light upon bodies for
heating them, and putting their parts
into a vibratory motion, wherein
heat confifts ?
There are .various othqr opinions
concerning the nature of fire and its
method of action, which though dif-
ferent from what has been offered,,
are not lefs probable : I will con-
tent myfelf with mentioning two
ttiore.
Boerhaave thinks that fire is a
fluid of a nature peculiar to itfelf $
that it was created fuch as it is, and
, 3 cannot
C 159 )
cannot be altered in its nature or
properties, deftroyed or produced;
that it naturally exifts in ec]ual quan-
tities in all places; that it is wholly
imperceptible to our fenfes, and only
difcoverable by fuch effects as it pro-
duces, when by various caufes it is
for a time collected into a lefs fpace
than what, from its tendency to an
univerfal and equable difFufion, it
would otherwife occupy. All the
bodies- which are fituated in the im-
menfity of fpace, may, according to
this opinion, be divided into fire ex-
panding all other bodies,. and into all
the other bodies which are not fire,
but refift its action. The matter of
this fire is not fuppofed to be derived
from the fun in any wife ; the folar
rays, whether direct or reflected, are
of ufeonly as they impel the particles
of
( *6o )
of fire in parallel directions : that pa*
rallelifm being deftroyed, by inter-
cepting the folar rays, the fire in-
flantly refumes its natural flate of
uniform difFufion*. 'Confident with
this explication, • which attributes
heat to the matter of fire, when dri-
ven in parallel directions, a much
greater
* PofTent omnia corpora locata in fpatio
immenfo dividi in ignem expandentem -om-
nia reliqua corpora, et in caetera univerfa
corpora qnae non funt ignis Ignem il-
ium femper effe ubique praefentem, tarn in
pleno corporeo pleniffimo quam in vacuo
inaniilimo Ignem hunc aequabiliilime dif-
tribui tamdiu, qnamdiu non naicitur caufa
fmgularis in loco certo ignem hunc difper-
iiim c.olligens Ignem hunc non efle a
fole, quoad materiam ullo modo — Vim ignis
a fole determinatam in reftas parallelas re-
jnanere in omni tempore, quo emanatio vel
reflexio durat intercepta reclitudine ra-
cttorum a ible, ignem in parallelifmum agen-
tium, illico ceiiat jile paralielifmus, atq«e
ilatim illo ipfo rnomento ignis partes expan-
duntur aequabi liter quaquaverfum, — Boerh.
Chem. Vol. I.
greater muft be given it, when the
quantity fo collected, is amafTed into
a focus; and yet the focus of the
krgeft fpeculum does not heat the
air, or medium in which it is formed,
but only bodies of denfities different
from that medium*
• The author of the Let Ires Phy-
fiques is of opinion, that the folar
rays are the principal caufe of heat;,
but that they only heat fuch bodies
as do not allow them a free paf-
fage *. In this remark he is agreed
with Newton f; but then he differs-
totally from him, as well as from
B.oerhaave, concerning the nature of
^ the
* Les rayons du foleil n* echauffent les corps
<' V entant que les corps ne leur accordent {in
libre paiTagc a travers. Lett. Fhyf.
f Radii foli? non agirant media qua? perma-
naiu, nili i.i rcfiexioue et icfiactioue. Newt,
VOL. I. L
the rays of the fun. He does not
admit the emanation of any lumi-
nous corpufcles from the fun, or
other felf-fhining fubflances, but fup-
pofes all fpace to be filled with an
aether of great elafticity and fmall
denfity, and that light confiils in the
vibrations of this aether, as found
confifls in the vibrations of the air;
the particles of the one medium ex-
citing, by impulfe upon the organ
ofvinon, the idea we call light; the
particles of the other medium ex-
citing, by impulfe on the organ of
hearing, the idea we call found*.
But as a bell will not of itfeif begin
thofe
* La lumiere n'eft antre chofe qu* line agi-
tation ou ebranlement cause dans les parti-
cules de 1* ether qui fe trouve partout. — *
II n'y a done rien qui vienne actuellement
du foleil jufque a nous. Let. Phy.
( 1 63 )
thofe vibrations by which the air is
.put in motion, nor continue with
equal intenfity the vibrations, when
once excited., without the concur-
rence of fome mechanical caufe ; fo
neither will the fun either begin or
continue his vibrations, by which
the fuppofed sether is put in motion,
without a fimilar mechanical agency.
In afcending from eftecls to caufes
we muft ever arrive, upon whatever
hypothefis we proceed, at fome firft
caufe, which does not admit an ex-
planation from mechanical princi-
ples j this is evidently the cafe in the
prefent inquiry. Upon Newton's
fuppofition, the caufe by which the
particles of light, and the corpufclea
conftituting other bodies, are mutu-
ally attracted and repelled, is uncer-
tain. The reafon of the uniform
L 2 diffufioa
( 164 );
diffufion of fire, of its vibration,
and repercuflion, as dated in Boer-
haave's opinion, is equally inexplica-
ble; and in the lail mentioned hypo-
thefis, we may add to the other diffi-
culties attending the fuppotition of
an univerfal asther, the want of a
iirft mover to make the fun vibrate.
Theie are the opinions moft worthy
of notice, concerning elementary
fire; and of thefe it may be faid, as
Cicero remarked of the opinions of
philofophers concerning the nature
of the foul — harum fententiarum
) Deus aliquis viderit, qu<e
, me.gna queftio eft *.
But
* The reader who is defirous o'f making a
deeper inquiry into this matter, may coniult
a very ingenious tra#, entitled, Experiments
and Obfervafions on anirnal Heat, and the
lafiammation of combuitible Bodies, by Dr.
Crawford ;
.But befldcs this elementary fire,
which chemifts conceive to be every
where uniformly diffufed, they are
of opinion that fire enters, in dif-
ferent proportions, into the compo-
fition of all vegetables and animals,
and mod minerals ; and in that con-
denfed, compared, fixed ftate, it has
beea
Crawford ; and Mr. Scheele's Experiments
on Air and Fire, tranflated from the Ger-
man by Dr. Foriter, and illuitrated with judi-
cious notes by Mr. Kirvvan ; and a late work
of Wallerius', entitled Meditationes de Orig.
Mund.
May not the common degree of heat which
arifes from the mixture of different quantities
of the fame fluid heated to different degrees,
be inveftigated by the fame rule, by which
the common velocity of hard or non-elailic
bodies after their impact in the fame direclipn
is calculated, putting the momentum of heat
to be equal to its degree multiplied into thv
•quantity of heated matter ?
L 3
been denominated the phlogijfan.
Of itfelf, in-' its natural (late of im~
combined expanfion, fire is not ef-
teemed capable of ffiining, or burn-
ing; when chemically conjoined
with the other principles of bodies, it
is that alone which conceives and con-
tinues thofe motions by which bodies
are made to fliine, to burn, to con-
fume away. All bodies are more or
lefs fufceptible of combuftion, ac-
cording to the quantity of this princi-
ple which enters into their compo-
fition, or the degree of force with
which it adheres to them. In the act
of burning, and it may very probably
be during the fermentation, and pu-
trefaction, and chemical folutions of
various bodies, it recovers its fluidi-
ty, is expanded and difperfed into
the air, or combined anew with fuch
fubftances
iubftances as it has an attraction to-
Notwithstanding all that perhaps can
be faid upon the fubject, I am fenfi-
ble the reader will be ilill ready to
afk — what isfhlogifton ? You do not
furely expect that chemiftry fhould
be able to prefent you with a hand-
ful of phlogifbon, feparated from an
inflammable body; you may juit as
reafonably demand a handful of mag-
netifm, gravity, or electricity to be
extracted from a magnetic, weighty,
or eleclric body. There are powers
in nature which cannot otherwife
become the objects of fenfe, than by
the effects they produces and of this
kind is phlogifton. But the follow-
ing experiments will tend to render
this perplexed fubject Ibmcwhat
more clear.
If yon take a piece tf fulfkur,
L 4 and
( 168 )
andfet it on fire, it will burn intire-
Jy away, without leaving any afhes,
or yielding any foot. During the
burning of the fulphur, a copious
vapour, powerfully affecting the or-
gans of fight and fmell, and the ac-
tion of the lungs, is difperfed. Means
have been invented for collecting
this vapour, and it is found to be a
very ftrong acid. The acid thus
procured from the burning of ful-
phur, is incapable of being either
-burned by itfelf, or of contributing
towards the fupport of fire in other
bodies : the fulphur from which it
•was procured was capable of both :
there is a remarkable difference then,
between the acid procured from the
Tulphur, and the fulphur itfelf. The
acid cannot be the only conftituent
part of fulphur 5 it is evident that
fome thing
'fomething elfe mufl have entered into
its competition, by which it was ren-
dered capable of combuftion. This
fomething is, from its moft remark-
able property, that of rendering a
body combudible, properly enough
denominated the food of fire, the
inflammable principle, the phlogiftan.
From this analyfis we may con-
elude, that the conftituent parts of
fulfbur are two; — an inflammable
principle, which is difperfed in the
a6l of combuftion, and an acid. The
proportion of thefe parts has been
afcertained; and it is found, that in
any mafs of fulphur, the weight of
the inflammable principle is to that
of the acid in the proportion of 3 to
50*.
If
* The experiment from which this pro-
portion is derived, is laid to have been made
by
( 170 )
If you burn charcoal in the open*
air, and hold a glafs over its flame,
you will perceive that it burns with-
out emitting either any watery va-
pour or footy impurity; and nothing
will remain, from a large portion. of
charcoal, but afrnall portion of white
afhes, which are incapable of any
further combuftion. The principle
effecting the combuftion of the char-
coal, and difperfed by the act of com-
buftion, is the phlogifton.
If you fet fpirits of wine on fire,
they will, if pure, burn intirely
away : they differ from charcoal in
<*
this,
by M. Brandt with great accuracy about ths
year 1756. Spiclm. Chem. p. in. and Chem.
Diet. — Newmann from a limilar experiment
infers, that in 16 ounces of fulphur, there are
upwards of i$| ounces of pure acid, and not
quite £ of an ounce of the inflammable prin-
ciple. Newrn. Chem. p, i63.
6
( '7' >
this,: that they emit a vapour: but
they leave no refiduum. You may by
proper vefTtls collect the vapour of
burning fpirits,- and you will find it
to be an infipid water, incapable of
combuftion. The principle effect-
ing the combuftion of the fpirits of
wine, and difperfed by the act of
combuftion, is the phlogifton.
Some metallic Jubftances burn, when
fufficiently heated,, with a flame
more bright than that of fpirits of
wine, or charcoal; others burn or
fmother away like rotten wood; and
moft of them, when they have been
kept in the open air in a proper de-
gree of heat, lofe their metallic ap-
pearance,, arid are converted into
earth.. Thus red lead is^ the earth pro-
cured from the burning of lead ; and
fttfty, fuch as the polifliers of glafs and
marble
( '72 )
marble ufe, is the earth procured
from tin. The principle effecting the
combuflion of metallic fubftances,
and difperfed in the act of combuf-
tion, is the phlogiflon.
The acid of the fulphur ; the cjhes
cf the charcoal-, the water of the
fpirits of wine ; the earths of metallic
fubftanceS) are utterly incapable of
combuflion : their refpeclive dif-
ferences from fulphur, charcoal, fpi-
rits of wine, and metallic fubflances,
with refped: not only to inflamma-
bility, but to fmell, colour, co-nfift-
ency, and other properties, are at-
tributed to the phlogiflon which is
difperfed during the combuflion of
each of them.
This inflammable principle, or
phlogiflon, is not one thing in ani-
mals, another in vegetables> another
in
C 173 )
in minerals, it is abfolutely the fame
in them all, • juft as water which en-
ters into the compofition of flefh,
wood, coal, is ftill wat<jr, though its
exiftence and homogeneity be ren-
dered more doubtful in fome fub-
liances than in others. This iden-
tity of phlogiflon may be proved
from a variety of decifive experi-
ments ; I will feled a few, which may
at the fame time confirm what has
been advanced concerning the con-
flituent parts of fulphur.
From the analyfis or decompofition
of fulphur effected by burning, we
have concluded, that the conftituent
parts of fulphur are two- — an add
which may be collected, and an-*';;-.
flammable princip'e which is difperf-
ed. If the reader has yet acquired
any real tafle for chemical .truths,,
he
he will wifh. to fee this analyfis con-
firmed by fynthefis; that is, in com-
<mon language, he will wifh to fee
fulphur actually made, by combining
its acid with an inflammable princi-
ple. It feldom happens that che~
mifts can reproduce the original bo-
dies, though they combine together
all the principles into which they
have analyfed them ; becaufe not
only the number and proportions of
the principles, but the order alfo of
their arrangement muft be obfrrved,
before that can be effected : in the
inflance, however, before us, the re-'
production of the original fubftance
will be found complete.
As the inflammable principle can-
not be obtained in a palpable form
Jeparate from all other bodies, the
only method by which we can at-
tempt
C '75 )
tempt to unite it with the acid of
iulphur, muft be by prefenting to
that acid fome fubftance in which it
is contained. Charcoal is fuch a
fubftance, and by diililling powder-
ed charcoal and the acid of fulphur
together, we can procure a true yel-
low fulphur, in no wife to be diftin-
guifhed from common fulphur. This
fulphur is formed from the union of
tht acid with the phlogifton of the
charcoal ; and the charcoal may by
this means be fo entirely robbed of
its phlogifton, that it will be reduced
to afhes, as if it had been burned.
Animal fubftances reduced to the
flate of a black coal, will, by being
treated in the fame way, yield ful-
phur.
Spirits of wine, we have faid, con-
fift of phlogiflon united with water;
and
if we diftil a mixture of fpirits
of wine and the acid of fulphur, we
fhall towards the end of the opera-
tion obtain a pure fulphur.
. Oil of turpentine is very inflam-
mable, and confequently abounds
with the principle which has been
denominated phlogifton ; and from a
diflillation of acid of fulphur wirh
oil of turpentine, a fulphur may be
procured.
But one of the fhorteft and mod
obvious ways of illufcrating both the
compofition of fulphur and the phio-
giflon of metallic fubftances, is the
following. — Upon melted lead pour
the acid of fulphur ; collect the va-
pour which will arife, by holding a
very large ghfs or other veflel over
the melted lead, and you will, as foon
as the vapour is condenfcd, obierve
fevcral
feveral filaments of fulphur flicking
to the fides of the glafs. — When
lead is in a ftate of ftrong fufion,
its phlogifton is in a ftate of dif-
perfion : the acid of fulphur inftan-
taneoufly unites itfelf with this phlo-
gifton, and forms fulphur. It is pro-
bable, that fulphur might be pro-
cured by the fame means from a
variety of other bodies, when in a
Hate of actual combuftion.
I will in this place, by way of fur-
ther illuftration of the term phlogif-
ton, add a word or two concerning
the necefiity of its union with a
metallic earth, in order to conftitute
a metal.
Lead, it has been obferved, when
melted in a ftrong lire, burns away
like rotten wood ; all its properties
as a metal are deflroyed, and it is
VOL.I. M reduced
C
reduced to allies. If you expofe the
afhes of lead to a ftrong fire, they
will melt ; but the melted fubftance
will not be a metal, it will be a
yellow or orange-coloured glqfs. If
you pound this glafs, and mix it with
charcoal duft, or if you mix the afhes
of the lead with charcoal duft, and
expofe either mixture to a melting
heat, you will1 obtain, not a glafs>
but a metaly in weight, colour, con-
fiftency, and every other property
the fame as lead. This operation,
by which a metallic earth is reftored
to its metallic form, is called Reduc-
tion. The afhes of lead melted with-
out charcoal become glafs ; the afhes
of lead melted with charcoal become
a metal ; the charcoal then muft have
communicated Jomething to the allies
of lead, by which they are changed
from
from a glafs to a metal. Charcoal
conftfts but of two things, of allies,
and of phlcgifton -, the ajhes of char-
coal, though united with the afhes
of lead, would only produce glafs -,
it muft therefore be the other confti-
tuent part of charcoal, or phlogifton,
which is communicated to the afhes
of lead, and by an union with which
the afhes are reftored to their metallic
form. The afhes of lead can never
be reduced to their metallic form,
without their being united with fome
matter containing phlogifton ; and
they may be reduced to their me-
tallic form, by being united with
any fubftance containing phlogifton
in a proper ftate, whether that fub-
itance be derived from the ani-
mal, vegetable, or mineral kingdom
(for tallow, or iron filings may be
M 2 fub-
( *8o )
fubftituted with fuccefs in the room
of charcoal, in the experiment of re-
ducing the afhes of lead) ; and thence
we conclude, not only that phlogif-
ton is a neceflary part of a metal,
but that phlogifton has an identity
belonging to it, from whatever fub-
ftance in nature it be extracted. And
this aflertion ftill becomes more gene-
ral, if we may believe 'that metallic
afhes have been reduced to their
metallic form, both by the folar rays
and the electrical fire.
ESSAY
ESSAY V.
OF THE ORIGIN OF SUBTERRANEOUS
FIRES.
THE moft remarkable changes
which have taken place in the
form and conflitution of the earth,
fmce the deluge, have probably
been produced by fubterraneous fires;
for it is to their agency that philofo-
phers afcribe volcanoes and earth-
quakes ; thofe tremendous inftruments
of nature, by which fhe converts
plains into mountains, the ocean into
iflands, and dry land inco ilagnant
pools,
M 3 Dr.
Dr. Hooke formerly had main-
tained, that all iflands had been raifed
out of the fea by earthquakes ; and
modern philofophers feem to admit
his hypothecs, though not, perhaps,
in its utmoft latitude. Thus one of
them is of opinion, that Icelandy
which is bigger than Ireland, has
been produced by volcanoes in the
courfe of feveral centuries *. Ano-
ther, after giving an ingenious con-
jecture concerning the origin of all
the tropical low ijles in the South
Sea, afiures us, that of the higher ijles
there is hardly one of them which
has not flrong veftiges of its having
undergone fome violent alteration
by a volcano. Some of them have
volcanoes ftill fubfifting ; others,
amongft
* See Letters on Iceland by Dr. Uno Von
Troil, p. 222.
( 183 )
amongft which are 0-fabeitee and
Huaheinet feem to have been ele-
vated, in remote ages, from the bot-
tom of the fea by fubterraneous fires*.
When thefe fires were firft kin-
dled ; by what fort of fuel they are
Hill maintained ; at what depths be-
low the furface of the earth they are
placed j whether they have a mutual
communication ; of what dimenfions
they confifl -, and how long they may
continue, are queftions which do not
admit an eafy decifion. The fur-
face of the earth is admirably fitted
for the fupport of the exiftence and
well-being of all the animals which
M 4 inhabit
* Obfervations made during a Voyage
round the World, by Dr. Forfter, p. 152 ;
where the reader will find, in a note, a learned
reference to the works of a great many authors,
on the fubject of ifles raifed out of the fea by
the action of a subterraneous fire.
inhabit it. God has given us the abi-
lity alfb to penetrate a very little be-
low this furface -, and as the reward
of our induflry, he has placed with-
in our reach a great variety of ufe-
ful minerals ; but as to the central
recefles of the globe, we can never
penetrate into them. A gnat efTay-
ing the feeble efforts of its (lender
probofcis againft the hide of an ele-
phant, and attempting thereby to
invefligate the internal formation of
the body of that huge animal, is no
unapt reprefentation of man attempt-
ing to explore the internal ftrufbure
of the earth, by digging little holes
upon its furface.
But though it will ever be im-
poffible for us to fearch far into the
bowels of the earth, or to imitate,
in an extenfive degree, the great ope-
rations
( '8$ )
rations which are conftantly carry-
ing on beneath its furface, yet it
affords a curious mind no mean
degree of fatisfa&ion to be able, by
obvious experiments, to form fome
reafonabJe conjectures concerning
them.
Mr. Lemery *, as far as I have
been able to learn, was the firft per-
fon who illuftrated, by actual expe-
riment, the origin of fubterraneous
fires. He mixed twenty- five pounds
of powdered Julphur with an equal
weight of iron filings; and having
kneaded the mixture together, by
means of a little water > into the con-
fidence of a pafte, he put it into an
iron pot, covered it with a cloth,
and buried the whole a foot under
ground,
* Cours de Chemie, p. 876. & Mem. de
1'Acad, des Scien. a Paris, An. 1 700.
ground. In about eight or nine hours
time the earth fwelled, grew warm,
and cracked $ hot fulphureous va-
pours were perceived; a flame which
dilated the cracks was obferved ; the
fuperincumbent earth was covered
with a yellow and black powder : in
Ihort, a fubterraneous fire, producing
a volcano in miniature, was fponta-
neoufly lighted up from the reciprocal
actions of fulphur, iron, and water.
That part of this experiment
which relates to the production of
flre> by the fermentation of iron
filings and fulphur when made into
a jzfoite *, has been frequently re-
peated
-: The words ferment and fermentation may
perhaps be improperly applied to the fponta-
neous tranfpotition of parrs, which takes place
in mineral fuljlanccs ; but the reader cannot
fail to underltand what is meant by them when
thus applied.
C 187 )
peated fince the time of Mr. Le-
mery. I myfelf have made it more
than once, but I have nothing ma-
terial to add to his account, except
that the flame, when the experiment
is made in the open air, is of very
(hort duration ; and that the whole
mafsj after the extinction of the
flame, continues at intervals, for a
longer or fhorter time, according to
its quantity, to throw out fparks ; and
that a ladle full of the ignited mafs,
being dropped down from a confi-
derable height, defcends like a Ihower
of red-hot aflies, much refembling
the paintings of the eruptions of
Mount Vefuvius, which may be feen
at the Britifh Mufeum. It has been
obferved, that large quantities of
the materials are not requifite to
make the experiment fucceed, pro-
vided
vlded there be a due proportion of
water : half a pound of fteel filings,
half a pound of flour of brim-
ftone, and fourteen ounces of wa-
ter, will, when well mixed, acquire
heat enough to make the mafs take
fire *.
That heat and fire Ihould be ge-
nerated from the fpontaneous actions
of minerals upon each other, is a
phenomenon by no means fingular
in nature, how difficult foever it
may be to account for it. The heat
of putrefcent dunghills, of the fer-
menting juices of vegetables, and,
above all, the fpontaneous firing of
hay not properly dried, are obvious
proofs that vegetables poffefs this
property as well as minerals. In
both vegetables and minerals, a de-
finite
* Sage Miner, Vol. I. p. 42.
finite quantity of moifture is requi-
fite to enable them to commence
that inteftine motion of their parts,
which is necefTary for the produc-
tion of fire. Iron and fulphur would
remain mixed together for ages
without taking fire, if they were
either kept perfectly free from
moifture, or drenched with too
much water; and vegetables in like
manner, which are quite dry, or
exceedingly wet, are incapable of
taking fire whilft they continue in
that flate *.
But
* Animal fubftances, when laid on heaps,
have been obferved to take fire. " M. Mon-
tet rapporte dans 1'hiftoire de 1* Academic
Royale des Sciences, annee 1776, que des pe-
tites etofFes appelles imperiales, gardees en
tas, prirent feu d* elles-memes. Inftruc.
fur 1> ufage de la Houille par M. Venel. It
is not improbable that filings of copper and
6 other
But though it is certain from the
experiment, that mixtures of iron
and fulphur, when moiftened with a
proper quantity of water, will fpon-
taneoufly take fire ; yet the origin
of fubterraneous fires cannot, with
any great degree of probability, be
referred to the fame principle, un-
lefs it can be fhewn that nature has
combined together in large quantities
iron and fulphur, and diftributed the
compofition through various internal
parts of the earth.
Now that this is really the cafe, we
can have no doubt. There is, per-
haps, no mineral more commonly
met
other metals, when mixed in a due proportion
with fulphur and water, would acquire a heat,
and perhaps take fire, efpecially if the quanti-
ties were large ; but experiments of this kind
have not hitherto been made.
met with, than that which is com-
pofed of .iron and fulphur. It is
found not only upon the furface of
the earth, but at the greateft depths
below it, to which mines have been
hitherto driven ; not only in Eng-
land or Italy, Europe or Afia, but
in all parts of the world. This mi-
neral is called, in fome parts of
England, copperas-ftone j in others,
brazil -, in others, br of s -lumps ; in
others, rufl-balls ; in others, horfe-
gold ; in others, marcafite ; though
naturalifts are now, I think, agreed
to give that name to fuch mineral
bodies as are angular and cryftal-
lized, efpecially into a cubical form.
The fcientific name is Pyrites, —
fiery ; a denomination expreflive
enough of the property which this
mineral
mineral has of ftriking fire with fteel>
and of fpontaneoufly taking fire, when
laid in heaps, and moiftened with
water.
Sulphur and iron are the chief
eonftituent parts of the pyrites ; arfe-
nic, however, is fometimes united
with the iron inftead of fulphur, and
fometimes fulphur and arfenic are
both of them combined with iron.
The pyrites alfo, accidentally, con*
tains copper, filver, and perhaps,
gold : hence the pyrites has been
diftinguifhed by mineralogies into
various forts, by attending, either to
its internal conftitution, as the iron,
the copper, the fulphureous, the
arfenical pyrites 5 or to its external
figure, as the pyramidal, the cubical,
the fpherical, the prifmatic pyrites ;
or
( '93 )
or to its colour, as the grey,
white, yellowilh, yellow, orange
pyrites *.
Though the reader may have never
contemplated the various fpecies of
the pyrites in any cabinet of natural
hiftory, or taken notice of fuch kinds
as are commonly to be met with in
chalk-pits, in beds of clay, or upon
the fea (hore in many places of Eng-
land, yet the yellowifh matter, often
adhering to or mixed with the fub-
itar.ce of pit-coal, cannot, fiirely,
have efcaped his obfervation : that
matter confifts of fulphur and iron>
and is a fpecies of the pyrites. So
much
* Whoever wifhes to become fully ac-
quainted with the natural hiftory of the py-
rites, may confult the Pyrltologla of Henckel,
where he will find the oiigin, nature, and
ufes of this mineral inveftigated with the
greateft learning and ingenuity.
VOL. I. N
much of this fort of the pyrites is
dug up together with the coal, at
Whitehaven, Newcaftle, and other
places, that people are employed to
pick it out from amongft the coal,
left it fhould vitiate its quality, and
render it lefs faleable. The pieces
of the pyrites which are feparated
from the coal, are not thrown afide
as ufelefs, but laid in heaps, for a
purpofe to be mentioned hereafter;
and thefe heaps, not many years
fince, tookjireboih at tPbitebavsn and
in the neighbourhood of Halifax.
The fame accident was obferved
above a hundred years ago at fuddle
Wharf in London, where heaps of
coal which contained much of this
pyrites tcokfre *.
Though Lemery was the firft
perfon
* Jorclen of Miner. Wat C. xir.
( 195 )
perfon who, by artificial mixtures
of fulphur and iron, produced fire,
yet that natural mixtures of thefe
fubftances would fpcntaneoufly take
fre, was known before he made hi&
experiment. Thus, to omit what
is faid by Pliny and the ancients, we
are told by good authority, that one
Wilfon at Ealand in Torkfhire, about
the year 1664 °r before, had piled
up in a barn many cart-loads of the
pyrites, or brafs-lumps, as they
were called by the colliers, for fome
fecret purpofes of his own : the roof
of the barn happening to be bad,
the pyrites were wetted by the rain ;
in this flate they began to fmoke,
and prefently took fire, and burned
like red hot coals**
We have an account, in the Phi-
N 2 lofophical
* Power's Miciof. Obfer. p. 62.
( '96 )
lofophical Tranfaftions for 1693 *,
of a covetous matter of a copperas
work at Wbtteftable in Kent, who,
in order to break his neighbour's
work, had engrofled all the pyrites
or copperas-ftone in the country : he
built a fried over two or three hun-
dred tons of thefe ftones, to keep off
the rain. In the fpace, however, of
fix or feven months, the mafs (being
probably wetted by the moifture of
theatmofp' ere, or by the rain, which,
notwithftanding the fhed, might have
fallen upon it) took fire and burned
for a week ; it quite deilroyed his
ihed, and difappointed all his hopes
of profit : for the pyrites was in part
converted into a fubftance like melt-
ed metal, and in part it looked like
red-hot ftones : all the fulphur was
con-
* No, 213*
( '97 )
confumed, and the neighbourhood
was miferably afflidted by the noxious
exhalation which it fent forth.
In the month of Auguft 1751, the
Cliffs near Cbar mouth in Dorfetjbire
took fire y in confequence of a heavy-
fall of rain after a hot and dry fea-
fon, and they continued at intervals-
to emit flame for feveral years. —
Thefe Cliffs confift of a dark-colour-
ed bituminous loam, in which are im-
bedded large quantities of different
kinds of the pyrites. The fame kind
of flame hasbeen frequently obferved
in the Cornifo mines, and this mine-
ral fire fometimes leads to the dif-
covery of a mine i but wherever it is
found to exift, the iron pyrites is
generally difcovered near it*.
There
* Philok Tranf. Vol. LIL, p
( 198 )
There are fome forts of earth
from which alum is made, which
abound fo much with the pyrites,
that the proprietors of the works are
forced to keep them conflantly well
watered, in order to prevent their
taking fire *, — But it would be ufe-
lefs to purfue this fubj eft further; we
have adduced proof fufficient, that
nature furnifhes materials, which,
under certain circumftances, may be-
come the occafion of fubterraneous
fires. The requifite circumftances
are a proper quantity of the mate-
rials, a proper portion of water to
moiflen them, and perhaps a com-
munication with the air may be ne-
ceffary. A fmall quantity ofthepy- '
rites
* Waller. Min. Vol. I. p. 25,— Henckel
Pyritol. p. 312.— Pvlinera. par M. Val. de
Bomare, Vol. I. p, 296.
rites is fufficient to kindle a fire ;
water is almoft every where found
in fuch great plenty below the fur-
face of the earth, that it constitutes
one of the greateft impediments to
our finking pits to any great depth;
and air, if it fhould be thought ab-
folutely neceffary to the fpontaneous
firing of the pyrites, may be con-
ceived either to accompany the wa-
ter in its dripping, pr to defcend
into the innermofc parrs of the earth
through the failures which are found
upon its furface. When a fubterra-
neous fire is once kindled, it may
be fupported for ages by other fub-
frances, as well as by tfcofe which
firil gave rife to it : thus, if a quan-
tity of the pyrites fhould take fire in
a flratum of coal, or of Jhale, or of
any other fubilance llrongly im-
N4 pregnated'
( 200 )
pregnated with bitumen, the fire
might continue till the ftratum was
confumed *.
There are fuch a great number of
volcanoes now fubfifling in every
quarter of the globe, and fo many-
unequivocal veftiges of others,
which in length of time have be-
come extinct, that fome philofo-
pliers think they have reafon on
their fide in fuppofing either, that
the earth, at fome confiderable dif-
tance below its furface, is furround-
td with a ftratum of ignited matter
of
* There are fome coaleries on fire now in
Scotland^ which were en fire in the time of
Agriccla. — Pennant's Tour in Scot. Part II,
p. 20 1. See an account of the coaleries on
fire in Staffordlhire, in Dr. Plott's Nat.
Hid. of that County ; and of the fubftances
fubiimed from the burning coal-pits at New-
caflle in Philof. Tranf. for 1676.
( 201 )
of a definite thicknefs $ or that the
whole central part of it is nothing
but a mafs of melted minerals*
which every where ftruggling for
vent, burfts forth where there is the
lead refiftance, fhivering into rude
fragments the fuperincumbent cruft
of earth, and deluging with moun- .
tainous torrents of liquid fire the
adjoining countries.
We do not know of what kind of
materials the inward part of the
earth is compofed ; the water, coal,,
earths, ftones, metals met with upon
its furface, have, bulk for bulk,
very different weights^ and a fimi-
lar inequality of fimilar materials
may take place at all depths below
the furface. Jt has been gathered,
however, from very ingenious ob-
fervations and calculations, upon the
at-
( 202 )
attraction of the hill Scbebattem in
Scotland, that the mean denfity of
the whole earth is about four times
and a half the denfity of water,
the mean denfity of ftones, fup-
pofe Portland (tone, being two times
and a half the denfity of water *.
Hence if this globe of earth could
be weighed in a fcale, it would re-
quire two equal globes and a half of
Portland flone, or four equal globes
and a half of water to balance it.
The whole earth being fo much
heavier, bulk for bulk, than the
general matter near its furface, it
has been conjectured, that there
muft be fomewhere within the earth,
towards the more central parts,
great quantities of metals, or fuch
like denfe matter, to counterbalance
the
* Philof. Tranf. 1778, p. 784.
the lightnefs of the fuperficial ma-
terials, fo as to make up the whole
weight of the earth. Suppofing the
diameter of the earth to be 7920
miles, and that it was compofed of
an inward globe 5110 miles in dia-
meter, and of an outward fpherical
fnell 1405 miles in thicknefs, the
matter of the inward globe being as
heavy nearly as melted filver, and
the matter of the outward cruft be-
ing as heavy, at a medium, as Port-
land ftone ; then would the weight
of fuch an inward globe, and fuch
an outward (hell or cruft, be toge-
ther equal to the prefe-nt weight of
the whole earth. But confidering
the great compreflibility of water,
and of the Hones and earth met with
upon the furface of the globe, it is
probable, that in* defcending to-
6 wards
( 204 )
wards its centre, the parts may be
fo. condenfed as to make the weight
of the earth what it is, without fup-
pofing its central parts to be com-
pofed of materials different from
its fuperficial parts *.
But to return to our experiment.
I need ufe no arguments to prove
that either the fulphur, or the iron*
or both, have undergone a great
change during their fermentation :
we can have no difficulty in think-
ing that the fulphureous fleams,
heat, flame, and fire, which attend-
ed the mutual action of fulphur and
iron upon each other^could not have
been produced without the bodies
themfelves having fuffered fome
change : this change is vifible from
infpedl-
* See Mr., Mitchell's very ingenious EfTay
on Earthquakes.
( 205 )
infpecYmg the mixture before and
after its fermentation ; from a grey-
ifh colour it will be turned wholly
black, or of a deep red ; it will be
rendered more manifeft by tailing
it : neither iulphur nor iron have
any tafte, nor has the mixture of the
two any tafte before its fermenta-
tion; but after that is finifhed, it
has a very faline talte. The nature
of the fait contained in it will be
examined in the next eflay.
ESSAY
ESSAY VI.
OF VITRIOLS, AND THE REPUTED
TRANSMUTATION OF IRON
INTO COPPER.
nature of the refidue re-
JL fulting from the fermentation
of iron filings and fulphur, may be
eafily afcertained. Its tafle indicates
that it contains fome faline fub-
flancej in order to fee what that
fubftance is, it muft be boiled in
water; by this -means all the fait
contained in it of whatever quality-
it may be, will be extracted. The
water containing the fait in folu-
tion being filtrated, evaporated, and
cry-
( 208 )
cryftallized, according to the ufual
mode, we fhall obtain large faline
cryftals, of the colour of an eme-
rald, and of the figure of a lozenge.
This fait is called green vitriol ;
green from its colour, and vitriol
from its refembling vtirum, or glafs,
by its transparency.
This fait certainly did not exift,
either in the fulphur, or in the
iron, it mud therefore arife from
their mixture ; but from a mere
mixture of fulphur and iron, no
felt can be extracted, unlefs the
fubftances of which it confifls
have been, by fome means or
other, ciecompofed. The reader
may probably recollect, that ful-
phur is compofed of two things, —
of an acid> and of phlogifton. — Iron
alfo is compcfed of two things, — of
an
C 209 )
an earth, and of phlogiftcn. During
the fermentation of the mafs of ful-
phur and iron, the phlogifcon, or in-
flammable part of them both, is.dif-
perfed ; and, indeed, in being dif-
perfed, it becomes the caufe of the
heat, fire, and flame, obfervsble in
that mafs. The inflammable part,
both of the fulphur and of iron, be-
ing difperfed, there remains the add
of the fulphur, and the earth of the
iron. The acid of fulphur is a very
ftrong acid, it difTolves many bodies
with great facility, and when it is
diluted with water, it, in particular,
diflblves iron; and, by its union with
the earth of iron, it compofes the
fait in queftion.
That this is a true explanation of
the origin of tfiis fait, will appear
'•evident from the following confide-
•VO..L. i. O ration.
< (210 )
ration. If into a quantity of the acrd
procured from the burning of ful-
phur, you put a piece of iron, the
iron will be wholly difiblved in the
acid, as fait is diffolved in water;
and if you faturate the acid with
iron, and then evaporate and cryftal-
lize the folution, you will obtain a
green vitriol, fimilar, in every re-
fpe&, to that obtained from the refi-
due of which we are fpeaking.
The compofition of green vitriol
has been fully explained, and its de-
compofition or analyfis will flili fur-
ther illustrate its nature, and leave
no doubt of the truth of the propo-
fition which aflerts, that green vi-
triol confifts of the acid cf Julpbur
united to iron, w more properly to
the earth of iron.
If you put 1 6 ounces of frefli
green
( 211 )
green vitriol into a retort, and diftil
them till nothing more can be forced
into the receiver, by the utmoft
violence of a long continued fire,
you will find in the receiver about
1 1 ounces of an acid liquor, fmelling,
in all the trials that I have ever
made, very ftrongly of fulphur; and
in the retort you will find about 5
ounces of an earth, of a deep red, or
purplifh colour* The acid liquor,
by combining it again with 'iron,,
may be made into vitriol ; and the
earth, by being properly melted in
conjunction with any matter which
will reftore to it its inflammable prin-
ciple, may be made into iron. The
proportionable quantities of acid and
earth procurable from green vitriol'
by diftillation, are purpofely expref-
fed in terms rather indefinite, becaufe
o 2 that
that proportion is fomewhat variable
in different vitriols.
The earth remaining from the
diftillation of vitriol is called Colco-
thar. I would not have troubled the
reader v.rith fo barbarous a name,
but for an obfrrvation relative to
its ufe, which may be worth men-
tioning.
Colcotbar is fold for ten-pence a
pound in Pans; it is ufed for giv-
ing the lad polifh to plate-glafs, at
the great manufactory in the flreet
St. Anioine. The large ft plate of
glafs which had ever been polifli-
ed in that manufactory, they in-
formed me ten or twelve years ago,
was ten feet in length, and fix in
breadth. The glafs is brought from
Picardy, it is there melted in large
crucibles, and fpread, whilil liquid,
upon
upon a table covered with a flieet of
copper 5 much after the fame man-
ner in which plumbers caft a iheet of
lead. The plate of glafs, when firfl
caft, is an inch in thicknefs; its
afperities are ground away with a
coarfe kind of grit-ftone, with fand,
and emery, of different degrees of
finenefs, and it is at laft polifhed by
colcothar.
I do not know whether the ufe of
colcothar is adopted in our Englifh
plate-glafs manufactory near Prefect
in Lancashire ', having not been fortu-
nate enough to obtain permiffion to
fee it. But, both to the proprietors
of that manufactory, and to the pa-
tentees for polifhing marble at AJh-
ford in Derbyfoire> I take the liberty
to fugged, that colcothar, which is
very cheap, might perhaps render
o 3 the
the ufe of putty, or calcined tin, left
necefTary.— Would it not be poffible
to apply the fame kind of machines
by which marble is polifhed to the
polifhing of plate-glafs ? — But to
return from this digrefiion*
The acid feparated from vitriol,
by diftiilatipn, is called the vitriolic
acid. From what has been faid, rela-
tive to the formation of vitriol, it
manifeftly appears to be the fame
with that which enters into the com-
poiition of fulphur; and indeed the
main part of what is fold as vitriolic
acid is now obtained by collecting
the vapour of burning fulphur, and
not, as it ufed formerly to be, from
the difliilation of vitriol.
It muft not be imagined, that the
acid liquor procured from the diftil-
lauon of the 16 ounces of vitriol,
confifts
confifts intirely of the vitriolic acid;
it confifts of that acid diluted with
a large portion of pure water. If
care had been taken to feparate the
different products as they arofe,
during the diftillation, we might
have procured, by a very gentle
fire, fix or feven ounces of water
wholly infipid : this is the water of
crystallization before fpoken of*; it
is called the phlegm cf vitriol. After
the feparation of this water, by a
ilronger degree of heat we fliould
have obtained an ounce or two of
water (lightly impregnated with an
acid : this is called, fpirit of vitriol.
Laftly, with a very violent fire, we
ihould have gotten a very ponderous
and ilrong acid, having an unctuous-
appearance, and from that appear-
o 4 ance-
( 416 )
ance generally, but improperly, cal-
led, oil cf wit rial. This oil of vi-
triol is not always fluid ; fometimesj
when it is exceedingly ftrong, it has
been obferved to become folidj in
that ftate it is denominated, glacial1
or icy oil cf vitriol.
It was fhewn in the lad EfTay, that
natural- combinations of iron and
fblphur were fubjecl: to the fame
fpontaneous changes obfervable in
the artificial mixtures of thefe fub-
jftances ; and hence we may clearly
apprehend the manner in which
what are called native- vitriols are
formed in mines and other fubterra-
neous cavities* The pyrites exifting'
in thefe places being naturally de^
compofed by the fulphur's parting
with its phlogifton, the water which
is always dripping in mines, diflblves
the
the vitriol generated in the decorri-
pofed pyrites; and being afterwards-
evaporated, either by the heat, or the
current of air fubfifting in the mine,,
the vitriol is- found in its cryftalline
form, either projecting like icicles
from the top and fides of the mine,
or lying in cavities at its bottom.
The cryftals of native vitriol are
more or lefs regular, according to the
circumftances attending the evapo*
ration of the water, and they are of
different colours according to the
quality of the pyrites; for together
with the fulphur and iron, the chief
conflituent parts of the pyrites, there
is fometimes combined copper,, and
other metallic matters, which being
diifolved by the acid of the fulpbur
at the fame time that the iron is dif-
folved, a mixed vitriol is produced,
the
( 2.8 )
the colour of which is fometimes
whitifh, more generally it confifls of
different fhades of green and blue.
Native vitriol is often met with in
our coal mines. From an old Cannel-
coal pit near Wlgan in Lancafhire, I
procured a confiderable quantity of
it very well cryftallized -, and Dr.
Rutty has obferved, that the vitrio-
lic water at Haigh in Lancashire is
the ftrongeft in Britain, yielding
1920 grains of vitriol from a gallon
of water*.
When I was at Wbitebaven fome
years ago, I was informed by the very
intelligent fuperintendant of the coal
works in that place, that the bottom
of
* Philof. TranlV 1756. p.. 650. See alfo
for an examination of this Haigb water, which
fprings from a ilratum of the cannel-coal,.
Leigh's Tentamen Philo. ds Fonte ;Med. in
Agro Lancai. C\ L
of a pump of caft iron, which had
flood a long time in a well of vitriolic
water, was fo much foftened, that,
after removing a thin coat of ruft,
he was able to cut it with a knife,
as eafily as he could cut black leadj
it had preferved its grain, and was not
in any wife altered, except in being
foftened.
At that time, I attributed this
foftening of the iron, to the action of
the vitriolic water, and thought it a
very fingular phenomenon : in thisy
however, I was mifta'kcn; fea water
has the fame effect. Some iron can-
non, which had lain in the fea up-
wards of fixty years, were weighed
up, and the iron was found to be as
foft as tin ; though in 24 hours, by
being expofed to the air, it recovered
its
( 220 )
its original hardnefs, *. This foften-
ing of iron is not an effect peculiar
to the a&ion of either vitriolic or
fea water : I have fomewhere read of
an experiment of foftening iron by
fmearing its furface with the acid of
vitriol; and I have heard of a gen-
tleman, who having frequently ftir-
red faline draughts with his pen-
knife, found its temperature much
foftened thereby. Dlodorus Siculus
mentions a cuftom of the Celtiberiansy
by which they made their arms of
incomparable hardnefs i they buried
plates of iron under the earth, till the
weaker part of the iron was confumed
by the ruil, and they fabricated their
arms from the remainder^. The
inhabi-
* Hift. de PAcad. des Scien. a Paris, aru
1756.
t Diod. Sic» L. V. p. 356.
( 241 )
inhabitants of Japan are faid to
make life of the fame artifice*. —
The time, however, in winch the
iron is fuffered to lie in the ground,
muft not be too long; for the iron,
inilead of being foftened and melio-
rated, will in length of time be
wholly changed, as is faid to have
happened to tome Spanifh cannon
made of hammered iron, which had
lain many years under the old fort
at
* In itinerariis referunt aliqui de Japanen-
fibus quod ferrum fuum in contos excuium
locis paluitribus immergant, et ibi tamdiu re-
linquant, dum ad inultam partem ferrugine
fit confumtum ; exemtum dein e novo exeu-
dant, et iterum in palude per ipatium 8 vel
10 annorimi recondant, utque dum iterum
in aqua paludinofa falfa adrnodurn exeiuru fit :
pars ferri quae reftat fpecieui chalybis referre
perhibetur, exinde dein vomeres fabricant, ex-
que ferro fie rubiginofo inflruraenta fua et uten- ,
filia confidunt. Sweden de Ferro, Vol. I,
p. 194.
( 222 )
at Hull in Tcrkfbire-, the iron being
changed into a brittle kind of
ftone refembling an iron ore, and
refufmg to obey the action of the
magnet*.
Modern chemifts apply the name
vitriol^ to every combination of tlje
acid of fulphur with any metallic
fubftance ; three, however, of thefe
Combinations are more particularly
ciiftinguiihed, being of great ufe in
various manufactures ; — green vitriol
• — blue- vitriol — white vitriol.- The
acid in all thefe vitriols is the fame:
the metallic bafis of the green vitriol
we have already feen is iron, that of
the blue vitriol is copper, and that
of the white vitriol is zinc. Vitriol is
very commonly called by the manu-
facturers coffer as: thus we con-
flantly
* Lifter's Journey to Paris, p. 14. Ed. 1699.
ftantty hear of green, blue, and
white copperas. The con'lituent
parts of the different kinds of vi*
triols were not understood by the an-
cients fo well as they are at prefent;
they feem to have had an idea, that
copper was the bafis of them all :
hence the Greek term for vitriol,
chahanthos, the efflorefcence of cop-
per ; and the Latin one, cuperofa, or
cupri rofa^ the flower or efflorefcence
of copper ; from which the French
toupercfe, and our copperas, are evi-
dently derived.
The vitriols which nature pre-
pares, are never to be met with in
commerce ; they ferve to adorn the
cabinets of the curious, but they are
neither fufficiently pure for the pur-
pofes to which common vitriols are
applieJ, nor are they found in fuffi-
4 cient
cient quantities to anfwer the de-
mand which is made for them.
Green vitriol is made at Depfford*
and other places, from a fpecies of
the pyrites found onSbtfpey Ifle, the
Ifle of Wight, and various parts of
the Effexy Kcntijb, SuJJex^ and Dor-
fetJJjire coafts. Large quantities of
the pyrites are laid in heaps in the
open air, on beds properly pre-
pared ; in half a year, a year, two
years, fooner or later, according to
its quality, the pyrites acquires a
fpontaneous heat; that heat without
being increafed to fuch a degree as to
fire the pyrites, infenfibly difperfes
the inflammable principle of the ful-
phnr, one of the conflituent parts of
the pyrites; the acid of the fulphur
being thus difengaged from the in-
flammable principle, unites itfelf to
the other principal conftituent part
of
cf the pyrites, the iron, and forms
green vitriol The vitriol thus
formed is wafhed from the pyrites
bed by the rain : the rain-water
which has diflblved the vitriol of the*
pyrites, cannot fink into the earth,
the bed on which the pyrites is
fpread being formed of clay ; and
being made, moreover, in a Hoping
pofuion, the diffolved vitriol runs
into receptacles properly placed to
receive it, and being boiled with
old iron till it is of a proper cor.-
fiflency, it is run off into coolers,
and left to cryflalliz?. Vitriol may
be made without the ufc of old iron>
but the liquor which drains from
thje pyrites being often not fatu rated
with iron, the iron is added to fatu-
rate the acid, and at the fame tiir.e
to purify it from any panic] ,s of
-VOL. i. P cc
( 226 )
copper it may chance to contain;
by this means a pure iron vitriol is
obtained., which i,s known in com-
merce under the name of Englifli
vitrioL The quantity of old iron, in
fome works, amounts to two hundred
weight in making a ton of vitriol.
Much after the fame manner, vi-
triol is made from the pyrites found
amongft coal; there are manufacto-
ries of it near Wigan, ^.Wblteba^en^
zt.Newcaftle upon fym, and in feve-
ral other parts of the kingdom.
But all the vitriol works have funk
in value of late years 5 the home
confumption of vitriol being much
diminished fince the acid, which
ufcd to be procured from the di~
ftillation of vitriol, has been ob-
tained from the burning of ful-
phur.
6 It
It is not eafy to determine when
this method of making, vitriol was
introduced into Englaadv Dn the
very beginning of Queen Eliza-
beth's reign,, a patent was granted
to Cornelius Devoz, for making
alum and copperas * ; but it was
not till towards the end of the lad
century, that this art of making
vitriol was brought to fo: great per-
fection as to enable us, to export any
of it f j and, indeed J, a, very- deep
and judicious inquirer into things of
this- kind affures us-, that " at the
latter end of the lair, century, we im-
ported annually about 500 tons of
vitriol, arrd that we now export up-
wards of 2000 tons." It appears,
that there were exported, from the
p 2 pore
* Oper. Min. esplicat. p. 26.
f Boyle's Works,
t Canipb, Survey of Brir. Vol.11, p. 21.
'.port of London alone, near 400 tons
of copperas in three months, Janu-
ary, February, and March, 1776 *.
A fmall quantity of vitriol, perhaps
to the annual amount of 50 or 60 tons,
is ftill imported into England; feme
particular dyers and other artifts
being of opinion, that the foreign
vitriol, as containing a little copper,
is more ufeful to them than the
Englifli vitrioL
It may eafily be known whether
green vitriol contains any copper;
we need only rub the vitriol to be
examined upon a moiftened piece of
poliflied iron, for if there is any cop-
per in its competition, the iron will
be changed into a copper colour.
This -experiment renders it neceffary
to
* See Sir Charles Whitworth?s Reg. of
Trade, No. I.
to explain to the reader two terms
frequently met with in ehemical
books — affinity and precifitation.
When two heterogeneous bodies,
as an acid and iron, coalefce toge-
ther, and conftitute by their union
a third body different from either of
them, their union is faid to proceed
from their mutual attraction, "or, in
the language of German philofo-
phy, from their mutual affinity. It
may reafonably be conjectured, that
the affinity of the fame body, of the
fame acid for inftance, may be dif-
ferent with different bodies j its ac-
tion upon iron may be different from
its action upon copper ; and its ac-
tion upon any metallic fubftance
may be different from its action-
upon any alkaline or -earthy fub*
becaiifc, fiorrr whantverat-
•P. 3. tractive
tractive powers we fuppofe its action
upon any body to proceed, it feems
probable enough, that their effects
will be modified, according to the
nature of the fubject upon which
they are exerted, A few inftances
will make this matter clear.
Spirits of wine very readily dif-
folve a portion of camphor ; that is
the particles of the fpirits of wine
fo powerfully attract the particles
of camphor, that they unite them-
felves with the camphor in fuch a
way as to compofe with it a pellu-
cid fluid. Spirits of wine, however,
more powerfully attract water than
they attract camphor; for if you
mix water with camphorated fpirits
of wine, you will fee that the fpirits
quitting their connection with the
camphor, will unite themfelves with
the
the water, and the camphor being
lighter than water, will rife up to
the furface. Lavender water con-
rifts of the oil of lavender difTolved
in fpirits of wine. Into a glafs of
water, drop a few drops of lavender
water ; the fpirits of wine will quit
the oil, in order to unite themfelves
with the water, and the oil being
lighter than water will float upon its
furface. In both thefe cafes, the'
fpirits of wine are faid to have a
greater affinity with water, than with
camphor or oil of lavender.
Into a foluiion of green vitriol,
drop a folution of pot-afh, fait of
tartar or any alkaline fait ; the vi-
triolic folution will let fall a ftrdi-
ment: continue to mix the alkali
with the r.'iit'io'n of vitriol, till no
more rrVal 's to the bottom j the
p 4. matter
( 232 )
matter which falls to the bottom, is
faid to be precipitated, and it is often
called a precipitate. This effedtmay
be thus explained :. — green vitriol ,
confifts of two things, — of an acid,
and of an iron earth $ but the acid
has a greater difpofition to unite it-
felfwith any alkali, than it has to
continue united with the earth of
iron ; when therefore an alkali is
prefented to it, it quits the iron
earth, which, thus wanting its fup-
port, falls to the bottom, and unites
itfelf with the alkali. The acid of
vitriol is therefore, on this account,
faid to have a greater affinity with any
alkaline fait, than with iron, becaufe
any alkaline fait will feparate the
iron from the acid. What is precipi-
tated may be ma3,e into iron ; and if
fhe liquid which floats upon the pre-
cipitated
C 2J3 )s
cipitated earthr be evaporated' and -
cryftallized, ic will give the very
kind of fait which would arife from >
a direct combination of the acid of
vitriol with the alkali which occa-
fioned the precipitation. I will
mention one other inftance.
Blue vitriol confifts of copper
united with the acid of vitriol : if to
a folution of blue vitriol you add a
piece of bright iron, it will prefent-
ly become covered with a coppery
coat, the copper will all bz precipi-
tated, and the iron will be diffolved.
in its ftead. The proof of this rea-
foning is eafy : the matter which is
precipitated may be melted inter
copper, and the liquid part may,,
by evaporation and cryftallizarion,
be made, not into blue^ but into^^w
vitriol) that is, into a combination of
the
( 234 )
the vitriolic acid andiron. Hence it
is faid, that the acid of vitriol has a
greater affinity with iron> than it has
with copper, becaufe it quits cop-
per to unite itfdf with iron. lit
order to be convinced of the truth of
what is advanced, we need only dip
a bright key into a folution of blue
vitriol, and we ihall fee the key pre-
fently becoming covered with a
copper-coloured pellicle.
This experiment explains to u£,
in a very fatisfadlory manner, the
nature of that tranjmutatwn cf iron
into copper t which travellers have
been fo much furprifed at. Agricola
fpeaks of waters in the neighbour-
hood of Niwjol in Hungary which
had the property of tranfmuting the
iron which was put into them into
copper*. In the year 1673, our
coun-
* Agric. Fof. L. IX. p. 347.
countryman Dr. Brown vifited a fa-
mous copper mine at Herrn-Grundi '5
about feven Englifh miles from
•New/of} he informs us that he there
faw two fprings, called the old and
new ziment, which turned iron into
capper. The workmen fhewed him
a curious cup made of this tranf-
muted iron ; it was gilt with gold,
had a rich piece of filver ore fatten-
ed in the middle, and the following
infcription engraved on the outfide:
Eifen ware icb± kupfer bin ich,
Silver trag ich, gold bedeckt mich.
Copper I am, but iron was of old,
Silver I carry, covered am with gold*.
It was even at that time, he fays,
contended by fome, that there was
no real tranfmutation of iron into*
copper,
* Brown's Travels, Ed. 1687, p. 69.
( 2J6 )
• J 1
.copper, but fnat the zimeat watev
containing vitriol of copper, and
meeting with the iron, depofued its
copper ; and it fe^ms as if he would
have acceded to this opinion, could
he have told whatbecame of the iron.
It is now very well underftood what
becomes of the iron ; it is taken up
by the water, and remains fufpended
in it, in the place of the copper ;
fo that this tranfmutation is nothing
but a change of place; and as the
copper is precipitated by the iron,
fo the, iron might be precipitated by
^ r\ *T* t ^i^iTVf'f}^
pot-afh,orany other fubftance which
has a greater affinity with the acid
of vitriol than iron has.
The caufe of the impregnation of
thefe copper waters in Germany is-
now difficult to be explained. Mofb
copper ores contain futyhur, and
when
( *37 )
when the fulphur is in any degree de-
compofed, its acid unites itfelf to th-e
copper, and forms blue vitriol, which
is the fubftance with which the wa-
ters ifTuing from the copper -mines
are impregnated. It has been the
cuftom in Germany, for fome centu-
ries, to colled: the copper contain-
ed in thefe waters ; the method is
fimple: into pits filled with the cop-
pery water they put old iron; theiron
is difiblved, and the copper is pre-
cipitated, and being raked out in
the form of mud, it is afterwards
melted into very fine copper. The
quantity of copper procured by an
hundred tons of iron, is not always
the fame ; 'it fometimes amounts to
90 tons, and feldom to lefs than 84*.
The
* Mifcei, Curi. Germ. Ann. 6 & ;, p. 158,
where1
progrefs of arts is in many
inftances wonderfully flow. Though
this method of obtaining copper has
been long practifed in Germany, yet
it is but of late years that any fuc-
cefsful attempts of this kind have
been made in either England f or
Ireland 5 and that they have been
made at all has, in Ireland at kaft,
been owing not to the example
which had been fee in Germany,
but to an accident.
There are very celebrated cop-
per-mines. ztArklow in the county of
Wicklow in Ireland 3 and from thefe
mines
where there is mention made of an oak leaf
being changed into copper— -the iron con-
tained in the leaf, probably precipitating
the copper.
f An attempt was made in 1571, to tranf-
rnute iron into copper-, near Pool in Doriet-
fliire. Hutch. Hift. of Dori. Vol. II. p. 1 1 o.
( 4.39 )
mines there iffues a great quantity
of water ftrongly impregnated with
the vitriol of copper. One of the
workmen having accidentally left
an iron fhovel in this water, he found
it fome weeks after, fo incrufted
•with a coat of copper, that it was
thought to be changed into copper.
The proprietors of the mines, in
purfuance of this hint, made proper
pits and receptacles for the water,
and have obtained, by means of foft
iron bars put into the coppery water,
fuch quantities of copper, as render
the dreams of as much confequence
as the mines. One ton of iron pro-
duces near two tons of copper mud ;
and each ton of mud produces, when
melted, 16 hundred weight of cop-
per, which fells for 10 pounds a ton,
more
( 240 )
fnore than the copper which is fluxed
from the ore*.
There is a mountain in the ifle
of Angkjey called Paris moun-
tain, which abounds in copper ore;
the bed of ore being above forty
feet in thicknefs. The leflees of
this mine annually raife between
fix and feven thoufand tons of mer-
chantable ore, and daily employ
above forty furnaces in fmelting
it. The ore is not rich in copper,
but it contains a great quantity of
fulphur, which muft be feparated
from it, before it ca*i be 'fluxed
into
* Phllof. Trarif. for 1751 and 1752, p.
502, and for 1756 — Iron often contains
gold ; the vitriolic acid has no action upon
gold ; is not the gold contained in the iro:i
mixed with the precipitated copper, and
it not be worth while on this account
afiay this copper ?
Into copper. The ore is accord-
ingly roafted ; the phlogifton, to-
gether with part of the acid of the
fulphur, is, by the violence of the
fire to which it is expofed in road*
ing, difperfed into the air ': another
part of the acid attacks and diflblves
.the copper. The water in which
the roafted ore is wafhed is fo ftrong-
ly impregnated with* copper, that
they have found it ufeful to adopt
the German method of precipitating
it by means of old iron, and they
have obtained in one year near one
hundred tons 6f copper precipitated
from this water.
The water, after the copper has
been precipitated by means of iron,
is at prefent thrown away; it would,
by evaporation, yield green vitriol;
and as above one hundred tons of
^OL. i. iron
iron muft be employed in obtaining
the fore-mentioned quantity of cop-
per, it may deferve to be confidered,
whether a manufactory of green vi-
triol might not be eftablifhed at
this and at all other places where
copper is obtained by precipitation.
One hundred tons of iron would
yield, at the lead, two hundred tons
of vitriol, which, at the low price
of three pounds per ton, would be
more than fufficient, I fuppofe, to
pay the expence of extracting it ;
efpecially, as means might be con-
trived of evaporating the watery fo-
lution, by a proper application of
part of that heat, which is at pre-
fent loft in all the great fmelting-
houfes. There are other purpofes to
which this water ,might be ufefully
applied, which I cannot infift upon
in this place. The
( 243 )
The principal ufe of green vitriol
Is, in dying and in making of ink.
When the vitriol is diflblved in wa-
ter, the iron contained in it becomes
black by the addition of an infufion
of gall-nuts. Galls are excrefcences
from the oak ; they are formed from
the exudation of the juices of the
oak : this exudation is not fponta-
neous ; it proceeds from the punc-
ture made in the bark by an infect :
in the hole which it has made, it de-
pofits its egg, and the exuding juice
hardening, forms a proper nidus for
it. Mod of the galls have holes
in them, the young infect having
eaten its way through the fubftance
in which it was hatched : in many of
thofe which have r.o holes, the in-
fecl may be discovered in the in fide,
by breaking the gall. The property
0_ 2 which
( 244 )
which an infufion of galls has, of
tinging a folution of vitriol black
or purplifh, renders it ferviceable
in difcovering the minuteft portion
of iron in chalybeate waters. I took
one grain of vitriol (a grain of vi-
triol does not contain quite half a
grain of iron) and difTolved it in 15
gallons of water ; the water, upon
the addition of an infufion of galls,
became fenfibly purple. Other aftrin-
gcnt vegetables have a fimilar efFecT:
on vitriol, but not in the fame degree.
I will conclude this fubjecl: with
mentioning an experiment, which,
when profecuted by a fkilful manu-
facturer, may, I fhould hope, fome
time or other, become of general
fervice.
I took a piece of dry oak, which
had been felled about a year -3 I
rafped
rafped off from the bark, from the
fap, and from the heart of the wood,
equal weights, and put them intQ
equal portions of hot water. After,
they had ftood fome time, it was
apparent that the bark had given
an higher colour to the water than
the heart had done ; and that the
water in which the fap was put, had
extracted the leaft colour. Into
equal portions of a folution of green
vitriol, I put equal parts of thefe
feveral infufions, expecting to have
feen the vitriol turned black by
them all ; but the event was, that
the fap infufion produced very little
change of colour ; the bark infufion
gave a dark brown ; and the heart
infufion inftantly gave one of the
rnoJ: vivid blues I ever faw. If the
rafpings of heart of oak be boiled
0 for
for an hour in water, they lofe this
property of forming blue with vi-
triol ; but the cold infufion forms
a fine blue $ and if a folution of
vitriol be poured upon the rafp-
ings, the whole is changed into a
blue mafs.
ESSAY
ESSAY VII.
OF NITRE, OR SALTPETRE, AND THE
APPLICATION OF ITS ACID TO THE
INFLAMMATION OF OILS, AND THE
CONGELATION OF QUICKSILVER.
SOME of the more ancient che-
mical writers were accuflomed
to make a diftmction between nitre
and Jaltpetre -, they are now ufe.d as
fynonymous terms. The conftituent
parts of nitre are two $• — an acid*
and the vegetable fixed alkali. This
proportion may be proved both by
the decomfofition and the comfofition of
nitre.
Nitre
Nitre may be decompofed'm the fol-
lowing manner. — Upon two parts
of nitre by weight, pour one part by
weight of ftrong acid of vitriol, and
diftil the mixture. You will obtain
thereby, a very ftrong acid, of a
yellowifh colour, and o/ a moll fuffb-
eating fmell, and which has the fin-
gular property of emitting red fumes ;
by the addition of water the colour
may be rendered blue or green^ but
the fumes will ftill be red. This is
the acid orfpirit of nitre * ; and it is
fometimes called Glauber's fuming
Jpirit of nitre, becaufe Glauber is
* The word fpirit is ufed by chemical
writers with great latitude j it is applied to
fields^ as the fpirit of vitriol, of nitre, of fea
fait, &c. and to 'volatile alkalies^ as the fpiril
of fal ammoniac, of hartfliorn, &c. and the
inflammable fluid obtained by diftillation frorrv
wine, &c. is eminently entitled to the name of
fpirit j.
gene-
( 249 >
generally fuppofed to have been the
firft inventor of this manner of ex-
trading it. — Two things werediftil-
led together, the acid of vitriol and
nitre. Nitre itfelf, we fay, confifts of
two things ; of a peculiar kind of
acid, and of the vegetable fixed
alkali : the acid, we have feen, may
be extracted by diftillation ; there
ought, therefore, to remain, in the
veilel ufed for the diftillation, the
acid of vitriol and the alkali of the
nitre: and there really does remain
nothing elfe ; for the refidue, whca
diflblved and cryftallized, is found
to be the very fame kind of fait, in,
all its properties, as would arife
from the direct combination of the
acid of vitriol with the vegetable
fixed alkali. We need not wonder>
that we do not find the alkali of
6 the
the nitre and the acid of vitriol irr
their feparate forms, but united to-
gether into a particular kind of fait ;
for the acid of vitriol has a flrong
difpofition to difiblve all kinds of
alkalies ; it attracts them with more
force than they are attracted by any
other acid $ and it was in confequence
of this fuperior attraction of the acid
of vitriol, that the acid of nitre was
difengaged from its other component
part : the acid of vitriol expelled,
as it were, the acid of nitre from
the fixed alkali, and fubftituted it-
felf in its place.
There are various other methods
of decompofing nitre, befides that
which has been mentioned : thofe
who prepare aqua fortis, ufually diflil
the nitre in conjunction either with
clay or with green vitriol, calcined
to
to a certain degree. The acid of vi-
triol is contained in many kinds of
clay, as well as in green vitriol ; but
it leaves both the clay, and the iron
of the green vitriol, to unite itfelf
with the alkali of the nitre j and the
acid of nitre being thus fet at liberty,
by the intervention of the acid of
vitriol, and being alfo of a volatile
nature, it is eafily made to afcend
in vapour, which, being collected
in proper vefTels, becomes the aqua
fortis of the fhops.
It may appear from what has been
faid, that the acid of nitre and aqua
fortis are but different names for the
fame thing ; the matter is not quite
fo, unlefs the reader will underftand
by aqua fortis, pure aqua fortis ; for
whenever the acid of vitriol, or any
fubftance containing it, is ufed in
the
the procefs for decompofing nitre by
diftillation, a portion of the acid of
vitriol is diftilied in conjim&ion
with the acid of nitre : hence the
common aqua-fortis may be confi-
dered as a pure acid of nitre, mixed
with a portion of the acid of vitriol.
This portion of the acid of vitriol is
thought to render the aqua fortis
fitter for the purpofes of fome par-
ticular artifts : thus engravers and etch-
ers ufe an aqua fortis which contains
about one tenth of its weight of the
acid of vitriol ; and the proportion
of acid of vitriol, which enters into
the aqua fortis ufed by dyers, is ft ill
much greater. It is neceflary for
refining /ilver, and for many other
purpofes, to have the acid of nitre"
quite pure. This may be effected,
cither by purifying the common
aqua
( 253 )
aqua fortis by various means well
known to chemifts, or by diftilling
nitre with fome fubftance which
contains no acid of vitriol ; for
though it be certain, that the acid
of vitriol is very ferviceable in dif-
engaging the nitrous acid from its
bafis, yet it is alfo certain, that the
nitrous acid may be difengaged,
without the afiiftance of the vitriolic .
acid : thus I remember having many
years ago obtained a very flrong
fuming acid of nitre, by diftilling
nitre with white Jand, which con-
tains no acid of vitriol.
The tartificial compofition of nitre
is eafily effected. Take a portion of
the nitrous acid, and pour it into a
folution of pot-alli, of fait of tartar,
or of any other vegetable fixed alka-
li> till no more effervefcence is ob-
ferved :
( 254 )
ferved : evaporate and cryftallize
the compound, and you will obtain
a perfect nitre. This ,is ufually
called a regenerated nitre ; and we
may often fee cryflals of nitre al-
moft inftantaneoufly produced, by
mixing a folution of pot-afh with
a nitrous acid of a due degree of
flrength.
In time of war with an enemy who
has plenty of pot-afh, but no falt-
petre, the fupplying him with aqua
fortis ought to be. prohibited under
as fevere penalties as the fupplying
him with faltpetre itfelf j becaufe,
if he can procure the aqua fortis, it
will be an eafy matter for him, by
mixing it with his pot-afh, to make
regenerated nitre. The nitre may
come a little dearer to him than com-
mon nitre would do , but it is at the
fame
fame time purer, and fitter for the
preparation of gunpowder.
Though chemiftry exhibits to us
a great variety of linking pheno-
mena, yet there is none more fur-
prifing than that which attends the
mixing of the fuming acid of nitre
with oil of turpentine. If you mix
thefe two fluids together in the
fevereft weather, and when they are
feverally colder than ice, you will
fee them inftantaneoufly catching
fire, and burfting forth into a dread-
ful flame. This experiment does
not always fucceed with the acid of
nitre which may ordinarily be pro-
cured from the fhops, becanfe it is
feldom fufficiently ftrong ; but when
it does fucceed, there is great danger
in making it, efpecially if the quan-
tities which are mixed together
amount
amount even to a few ounces. I
have feveral times feen a thick
column of flame and fmoke, above
.twenty feet in height, inftantane-
oufly produced, by pouring, at once,
a pint of the fuming acid of nitre
•on a pint of oil of turpentine. Who-
.ever undertakes to make a fimilar
inflammation, would do well to
ufe the precaution of fattening the
veflel containing the acid to the
end of a long pole, to prevent his
being burned by the drops of in-
flamed oil, which are difperfed, la-
terally, by the explofion, to a great
diftance.
•BorriMus, in the year 1671, is
thought to have been the firft perfon
\vho noticed the phenomenon here
fpoken of : fince that time the che-
mifts of all countries have employed
much
much attention in repeating and di-
verfifying this celebrated experiment.
In the Philosophical Tranfaclions
for 1699, we have a table expref-
frng, at one view, the effect which
the acid of nitre has upon a variety
of other oils, as well as upon the
oil of turpentine : we there find
enumerated 12 forts of oils, which,
when mixed with acid of nitre, efTer-
vefced, and exploded with a flame ;
1 8 forts which eifervefced, but did
not take fire; and 9 forts which
neither effervefced nor took fire. In
addition to the information contain-
ed in this table, we aie indebted to
the French chemifts, for a variety
of interefting memoirs on the inflam *
mation of oils •, both by the fimplc
nitrous acid, and by that acid when
mixed with the acid of vitriol. The
VOL. i. R reader
reader will, perhaps, be fatisfied
with a general reference to the moft
approved authors * on the fubjedt;
efpecially as there is not any very
fatisfadory folution given of the phe-
nomenon.
We know that a piece of iron may
be hammered till it glows with heat;
that the axle-tree of a carriage may
be fo heated, by the rapidity of the
motion, or the violence of the fric-
tion as to inflame the wood conti-
guous to it ; that two pieces of wood
may
* See Mem. de 1' Acad. de Par. Ann.
1701. 1726. 1747. and Macquer's Elem. of
Chem. Vol. II. p. 149. Eng. Tranf. and
efpecially Muflchenbroek's Additions to the
Experiments of the Florentine Academy. This
induftrious philofopher has there given us
above 200 different experiments, illuftrating
the change of temperature arifing from the
mixture of water; of fpirits of wine ; of vine-
gar : of the mineral acids ; with a great variety
«f other bodies.
( 259 )
may by fri&ion be made to take fire ;
and. we infer from thefe, and other
appearances of the fame kind, that
the motion excited by the action of
particular acids upon particular oils,
is fufficient to produce that degree
of heat which is requifite to inflame
the oils.
It does not feem to be a firnple
mixture of two ingredients which
produces heat ; they muil act upon
each other in a manner different from
what accompanies a fimple mixture,
and this action does not always take
place immediately. Thus, if we
mix 2 parts of fpirit of wine with
I part of frelh fuming acid of nitre,
the mixture will often remain cold
for near ten minutes., but it will at
laft begin to acquire a great degree
of heat, and it will boil with great
R 2 violence
violence for a confiderable length of
time. In like manner, by mixing
together equal bulks of ftrong acid
of vitriol and water, we may excite
a degree of heat greater than that
in which water boils : but it is not
a fimple mixture which takes place
on this occafion, the very texture
of the bodies feems to be broken;
for the compound occupies lefs fpace
than what the two ingredients would
have occupied, had there only been
a fimple mixture. A pint of water
mixed with a pint of oil of vitriol
will not make a quart, as it would
do, if mixed with a pint of milk ;
but then no heat would attend its
mixture with milk, and a very great
degree of heat attends its mixture
with the acid of vitriol. It cannot
be faid, that the acid of vitriol is re-
ceived
ceived into the pores of the water;
for then a fmall portion of acid
might be diflblved in a large portion
of water, without augmenting its
bulk * ; but the very form of the
bodies is changed ; there is, in the
words of Dr, Hooke, (who fitil ob-
ferved that acid of vitriol and water
when mixed together pofleffed lefs
fpace than when feparate) a penetra-
tion of dimenfions J.— Is heat ever ex-
cited by the mixture of two fluids,
when the bulk of the compound is
equal to the fum of the bulks of the
two ingredients ?
Strong acid of nitre, when mixed
with common water, or with fnow
water, produces a great degree of
heat; when mixed with water con-
R 3 gealed
* Philof. Tranf. 1770. p. 353.
% Haukfbee's Exp. Ed. 1719. p. 294*'
( 262 )
gealed into ice, or fnow, it produces
the greateft degree of cold which has
even been obferved on the furface of
the earth ; and this property of the
acid of nitre has given occafion to
one of the fined difcoveries of the
prefent century, — the conversion of
quickfilver into a malleable metal.
In the year 1759, upon the i4th
day of December old ftile, there was
obferved a greater degree of natural
(old at Peterjlurgh, than had ever
before been noticed, iince the time
that the Academy had kept Me-
teorological regifters ; Fahrenheit's
thermometer {landing at 66 degrees
below the freezing point. In a few
days the cold grew more intenfe, fa
as to make the thermometer, on the
26th of the fame month, fink to 744
degrees below freezing. This^ is
efteemed
C 263 )
efteemed the greateit degree of na-
tural cold which has hitherto been
obferved at Peteriburgh. This cold,
though very great when compared
with what we experience in Eng-
land in the fevereft feafons, is far
lefs than what is ordinarily felt in
Siberia ; 1 20 degrees below the freez-
ing point, having been often ob-
ferved; and on the ^th of January
I735? tne thermometer fell to 157
degrees below freezing *. When this
degree of cold was firil publifhed to
the world by Gmelinus, who made
the obfervation at Jenefeijk^ many
R. 4 fuf-
* In the treatife (Novi Commen. Petrop.
Tom. XI.) from which, this account is princi-
pally extracted,, trie degrees of heat and cold
are estimated upon the fcale of De Lifle's ther-
mometer ; but Fahrenheit's being more known
in England, I have every where fubftituted
the correfpondmg degrees of Fahrenheit's fcale
in the place of the other.
fufpe&ed the truth of the account,
or queltioned the accuracy of the
obfervation ; but their fufpicions
were ill founded, for an equal, if
not a greater degree of cold was ob-
ferved m Sweden in 1760-}- ; and we
ihall fee prefently that a cold even
greater than what is here mentioned,
has been experienced in other places
of Siberia, as well as at Jenefeifk.
Fahrenheit in 1729 had tried what
degree of artificial cold he could
produce, by diflblving pounded ice
in flrong acid of nitre : and he was
very much furprifed at the event of
his experiments, for the quickfilver
funk to 72 degrees below the freez-
ing point. Boerhaave calls this dif-
covery a thing incredible before, and
afks
f Novi Comm. Petrop. Tom. VI p. 39*
Sum. Dif.
C 265 )
afks with aftonifhment, what mortal
could ever have thought of it ? Na-
ture, fays he, had never produced a
degree of cold greater than 32 de-
grees below freezing; and all ani-
mals and vegetables expofed to fuch
a feverity of cold inftantly perifh-
ed*. In this obfervation Boerhaave
was certainly miftaken; for both
animals and vegetables can exift in
degrees of cold which are far fupe-
rior even to the utmoft artificial
cold which Fahrenheit produced.
Several philofophers have, at dif-
ferent times, repeated Fahrenheit's
experiment, but without being able
to produce a greater degree of cold
than he had done.
Profeflbr Braun, at laft, on the
14th of December, in the year be-
fore
* Boerh. Chem. Vol. I, p. 162.
( 266 )
fore mentioned, began his experi-
ments, with no other view than that
of producing a greater degree of cold
than any perfon had done before
him; for he rightly conjectured,
that the greater the degree of natural
cold prevailing in the air, the
greater would be that of the artificial
cold. With this defign he followed,
in his firft attempts, the procefs of
Fahrenheit, pouring the acid of nitre
on powdered ice; and he fucceeded
to his wifhes, having made the mer-
cury fink to 100 degrees below the
freezing point. With hopes of pro-
ducing a ftill more remarkable cold,
he continued his experiments; in
the courfe of which, having ufed all
his powdered ice, he fubftituted
fnow in its Head, and to his infinite
furprife and fatisfa&ion, he found
the
the mercury had defcended to 384
degrees below freezing. Sufpedt-
ing that his thermometer was broken,
he took it out of the mixture, and
found it uninjured; but he was be-
yond meafure aftonifhed at feeing
the quickfilver remain for fome time
immovable in the tube : it did not
begin to afcend till it had flood
above 12 minutes in a warm room.
He communicated this difcovery to
the Academy at Peteriburgh, on the
I yth of the fame month, and flated
the congelation of quickfilver as a
probable truth ; for he had con-
cluded it to be frozen, from its re-
maining for fo long a time immov-
able in a warm air. In a few days
he repeated his experiments, and
purpofely breaking the bulbs of fe-
veral thermometers, he obferved the
mercury
( 268 )
mercury to be congealed in them all*
This congealed mercury refembled the
moft polifhed filver in luilre; was
in found and confiftency like lead ;
for he hammered it, and cut it with
a knife, before the heat of the at-
mofphere reduced it to its former
fluid ftate. This wonderful difco-
very excited the attention of his col-
leagues in the Academy ; his expe-
riments were fuccefsfully repeated
by feveral of them ; and it was fur-
ther obferved, that folid mercury
funk in fluid mercury, after the man-
ner of metallic fubftances in general.
The congelation of quickfilver,
notwithstanding the accurate ac-
count given of it by Braun, and the
many eye-witnefles of the fad:, has
been queflioned by counfellor Leh-
man of Peterfburgh. According to
his
( 269 )
his obfervation, " the mercury cm-
ployed by profefTor Braun in his
experiments, was diftilled in the
common way, through water, and
the water only was frozen, and not
the mercury itfelf ; but having em-
ployed mercury diftilled without
water, and carefully purified from
all watery particles, the mercury
would not congeal, although com-
mon mercury did freeze when fet
in fnow mixed with fpirit of nitre,
or fpirit of fal ammoniac *." In re-
liance upon the juftnefs of this ob-
fervation, it has been affirmed that
mercury Cf is a femi-metal, which
continues fluid in the molt intenfe
freezing, either natural or artificial,
or
* Counfeller Lehman's Obfervations, quoted
by Dr. Foriler, in his Introdudion to Minera-
logy, 1768. p. 32.
or when both are combined/' I do
not think this objection of counfel-
lor Lehman of much weight, when
put in competition with the greac
number of experiments which Braun
appears to have made with accuracy,
and related with fidelity. He him-
felf hints at this objection, in the
fupplement which he publifhed to
the account of his difcovery ; but
he does not formally refute it, as
not thinking it of fufficient confe-
quence *. The vapour of difjtilled
mercury is indeed generally con-
denfed in water; but the mercury
is afterwards flrained through lea-
ther, and otherwife cleanfed ; fo that
I do
* Cogitarunt quidam merciirium forfitan
vel ob impuritatem, vel ob admixtam mercu-
rio aquam congelari, fed haec hypothecs quam
quidam fumferant, eft falliffima, omnem in
corporibu-s fieri congelationem ob aquam con-
tcntam. Novi Com.Petro. Tom, XL p. 307.
I do not apprehend that it contains
any water, efpecially that which is
ufed in thermometers ; for in mak-
ing of thermometers, the mercury
is expofed to a great heat, which
ould effectually diffipate any par-
ticles of water, if any were left ad-
hering to it.
The author of this fine difcovery
has made many experiments, in or-
der to determine what is the fmallefl
degree of natural cold which is re-
quifite to make the congelation of
quickfilver by an artificial cold,
ariiing from the mixture of acid of
nitre and fnow, fucceed ; and he is
of opinion, that the degree of na-
tural cold ought not to be lefs than
30 degrees below the freezing point,
to make the congelation begin ; and
that it ought to be 42 degrees be-
low
low freezing, to make the conge-
lation complete. It feems, if we
may rely upon thefe experiments,
that we ' can have very few oppor-
tunities of attempting on rational
grounds to freeze quicksilver, by
means of fnow and acid of nitre ;
for it very rarely happens that the
natural cold in England is 30 de-
grees below the freezing point, at
lead near the furface of the earth.
' This reflridtion is added on account
of fome obfervations which are faid
to have been made at Glafgow, in
January 1780. On the i4thof that
month, at fix o'clock in the morn-
ing, a thermometer placed upon the
fnow in the obfervatory park, flood
at 55 degrees below freezing, whilfl
one laid upon the fnow near the
furface of the earth, was only 18
i degrees
degrees below freezing. — This
difference probably proceeds from
hence, that the body of the earth
warms the air which is contiguous
to it, and thus counteracls the cold,
which may be accidentally gene-
rated in the atmofphere, more pow-
erfully near its furface, than at any
great height above it. It would
be worth while to obferve the tern*
perature of the air, at the bottom
and at the top of the Monument^
or any other high building in the
form of an obelilk, at all feafons of
the year, efpecially in winter time,
as greater degrees of cold may pr<o-
bably prevail, from the fall of fnow
and other caufes in the air, at the
top of an high building than at the
bottom, efpecially if the building
tapers up into a point, fo as not to
V.OL. i. S afford
( 274 )
afford, a great mafs of matter to heat
the ambient air.
The precife degree of cold requi-
fite co freeze mercury, cannot be af-
certained on account of the fudden
and irregular contractions which it
is obferved to fufFer, juft before it
begins to be folid j it continues to
defcen d$ after the part contiguous
to the bulb of the thermometer be-
gins to fre/ze; but probably, not
lefs than 600 degrees below freezing
are requi-fste to congeal it wholly.
It is remarkable, that oil of fafiafras
wood, of chamomile flowers, the-
liquor which remains from the boil-
ing of fea fait, and feveral other
fluids, continued uncongealed, in the
fame degree of cold in which mer-
cury was frozen.
Skx-e
( 275 )
Since the difcovery of the congela-
tion of quickfilver made by profeffor
Braun, philofophers have been very
attentive, in many places, to effect
the fame thing by the fame artificial
means; and they have fucceeded in
fome places, particularly at Albany
fort in Hudfon's Bay, where quickfil-
ver was frozen by Mr. Hutchins on
the 1 9th -of Ja nu ary, 1775, the cold
of the air then being 60 degrees be-
low the freezing point. In this ac-
count it is obferved, that the ftandard
thermometer, when taken out of the
mixture of acid of nitre and fnow,
-fell 10 degrees lower than when the
t>ulb was irnmerfed in the mixture.
A fimilar phenomenon had been ob-
ferved by profeffor Braun more than
-once ; and he accounts for it from
acid^ continuing to diffolve the
s .2 fcow
fnow adhering to the thermometer.
— May it not proceed from the
.quicknefs with which the moifture
adhering to the bulb -of the ther-
mometer, is evaporated, in confe-
quence of the great warmth of the
air when compared with the cold-
nefs of the moifture*? The Ruf-
fians being more favourably fituated
than moft other philofophcrs, for
making experiments on the effects
of cold, it .is from them that we
muft expeijt the further profecu-
tion of this fubject; I will therefore
lay before ttie reader, an account of
the .congelation of quickfiiver, by
the natur-al coldnefs of the atmo-
fphere, which prevailed at Krafnoy-
arjk, in the fouthern part of the
province of 'Toboljk : the account
is
.
* Philcf. Tranf, 1776, p. 174 & 590.
( 277 )
is tranflated from M. Paltafs Tour
through Siberia, Vol. IV. Part Hi.
cc The winter begun this year
very early, and was felt with uncom-
mon feverity in the month of De-
eember. On the 6th and yth of that
month, there was the hardeft froft
that I have ever obferved in Sibe-
ria; the air was calm,, and as it
were thickened; fo- that in a quite
clear fky, the fun wasfeen as through
a fog. On the fixth in the morning,
I obferved my thermometer, which
had been carefully made, but was
not graduated above 102 degrees
below freezing; the quickfilver was
funk into the bulb, except feme.
fmall pieces which were clodded to-
gether, and ftuck in the item : this-
was an accident which I had never
experienced with the fame thermo-
meter, though I had ufed it eight
years. Upon carrying the thermo-
meter into a warm room, the clodded
pieces fell immediately into the
bulb, but the quickfilvcr did not
begin to afcend till near a minute
after. I repeated this experiment
feveral times with the fame fuccefs,
there remaining in the tube fome-
times only one, fometimes feveral
little pieces of frozen quick/liver.
When the quickfilver in the bulb
was warmed by the application of a
finger, it prefently rofe; and it was
plainly feen, that the part which was
frozen in the item refilled the rife
of the quickfilver a confiderable
time, and was at laflthruft upwards,
. afcending with a fort of violence. I
cxpofed to the cold about a quarter
of
( 279 )
of a pound of quickfilver in an open,
vcflcl ; the quickfilver had been
cleanfed as much as poffible by vi-
negar and leather, and it was well
dried: in lefs than an hour its fur-
face was frozen, and in fome mi-
nutes after it was all condenfed by
the natural cold into a foft fubilance
like pewter. When the inner part
was yet in a fluid ftate, the furface
being broken, was wrinkled in fome
places, but the greateil part remain-
ed pretty even in freezing, as was
the cafe aifo with a larger quantity
of quickfilver, which was frozen
upon another occaiion. The frozen
matter of quickfijver was rnore.flexi-
ble. than lead, but more brittle than
pewter, and when hammered into
thin plates, it feemed fome what gra-
nulated j but if the hammer was not
s 4 per-
( 280 >
perfectly cooled, then the quickfil-
ver glided from it in drops; the fame
happened if it was touched by the
finger. In a warm room the quick-
filver thawed like wax over the fire*
and did not melt all at once. If the
frozen rnafs was broken in the cold,,
the pieces clung together and ftuck
to the fidtrs of the veiTel wherein
they were placed. Though the froft
towards the night feemed to abate a
little* yet the frozen quickfilver re-
mained unaltered, and the experi-
ment with the thermometer could
ft ill be repeated. On the yth of
December I had, during the whole
day, occafion to make the fame re-
marks j but fome hours after fun-
fetting, there came on a north-weit
wind, which raifed the thermometer
to 78 degrees below freezing, when
the
C *8r )
the quickfilver begun to difiblve.
Shortly afcer this, I was favoured
with an account from M. Lieutenant
General de Brtly Governor of Irkuzky,
that in the fame town at 4 o'clock
in the morning of the 9th of De-
cember, the mercury had been found
fafc frozen, both in the thermome-
ter and barometer, both of which
had been made by profefTor Lax-
man when he refided in Siberia. It
flood in the barometer 27 inches 7
lines, and the upper five lines were
quite broken, but it was liquid again
at ii in the forenoon. The thermo-
meter was clodded at 76 degrees be-
low freezing; and under the 91 ft
degree below freezing there was an
empty fpace of near 1 1 degrees. To-
wards 1 1 o'clock all was gone into
the globe, and at one o'clock when
it
( 28* )
it was again come into motion, it
fliewed 124 degrees below freez-
ing".
From thefe difcoveries of the Ruf-
fians we are fully authorized in con-
fidcring quickfilver as a metal, which
requires a greater degree of cold to
keep it in a folid ftate than is or-
dinarily met with upon the furface
of the earth : gold, and filver, and
iron, if carried nearer to the fun,
would be perpetually fluid ; and
quickfilver, if removed further from
it, would be perpetually folid; nay,
it may be fairly doubted, I think,
whether there may not be elevated
places upon the furface of the earth
cold enough to keep quickfilver in
a folid flate, at lead during the
greateft feverity of winter,
< ESSAY
ESSAY VIII.
OF THE MANNER OF MAKING SALT-
PETRE IN EUROPE, AND OF ITS
GENERATION.
QALTPETRE enters In a large
O proportion into the compofition
of gunpowder; hence, after the dif-
covery of gunpowder, all the Hates
of Europe were eager in their endea-
vours to amafs large quantities of
faltpetre, and ftudioufly fought out
various methods of preparing it; for
faltpecre is by many locked upon as
the produdion of art rather than of
nature.
Gun-
Gunpowder was very probably
made in England fo early as the year
1417. In Henry V.'s directions for
equipping his fleet with all requifites*
•under the general name jluffura> we •
find mention made of Carbonarii, and.
of vigtnti piparttm ds pit here de car bo ~
nibus Jaluh* : thefe twenty pipes of
willow-coal powder, could be for no
other purpofe, one would think, than-
for the making of gunpowder, if
gunpowder itfelf did not come under
that denomination. Three years be-
fore this, a proclamation had been
ifllied, forbidding the exportation of
gunpowder;, and in thofe early ages
of commerce, it may bethought un-
likely that gunpowder would be firft"
imported into England, and then:
exported again. Hollingflied, in his
Chro-
* RyraerVFceder. Tom. XI.-p. 543,-
Chronicle, fpeaks of the capture of
two French veflels in 1386, with a
great quantity of gunpowder, which,
he fays, was more worth than all the
reft of the cargo ; but had no gun-
powder been then made in England,
k would have been natural for him to
have mentioned that circumftance.
This, however, is mere conjecture,
and a more diligent fe arch into anti-
quity may, perhaps, (hew it to be ill
founded. There is a diverfity of tef-
timony on this fubject; one author*
afierting, that queen Elizabeth was
the firft of our princes who caufed
gunpowder to -be made in England;
anotherf informing us, that ahoufe
near the Tower, in which gunpowder
-was made, was blown up in the reign
of
* Baker's Chron. p. 399. Edit. 1696,
*f Holluigfhed's Chroo. year 155*.
C 286 )
of Edward the Sixrh, and fifteen
gunpowder-makers (lain by the ac-
cident. But, whenever gunpowder
was firfl made in England, it is not
without reafon, that we fuppofe it to
have been made of faltpetre manu-
factured in England; fince it is not
at all likely that any foreign power
would permit the exportation of fo
important, and, at that period, fo
fcarce a commodity.
Before fuch large quantities of
faltpetre were imported from the
Eaft Indies, the manufacturing of it
in England was much attended to ;
though it appears, from a proclama-
tion of Charles the Pirft, in the year
1627, that the faltpetre- makers were
never able -to furnifh the realm with
one third part of the faltpetre re*-
c[uifitc, efpecially in time of war.
This
This .proclamation was ifiued in
1627, in confequence of a patent
granted, in the year 1625, to Sir John
Brooke and Thomas RufTel, for mak-
ing faltpetre by a new invention*.
In this new invention, great ufe was
made of all forts of urine; for the
proclamation orders ail perfons to
fave the urine of their families, and
as much as they could of that of their
cattle, to be fetched away, by the
patentees or their afTigns, once in
twenty-four hours in the fummer, and
in forty eight hours in the winter fea-
fon. This royal proclamation was no
fmall inconvenience to the fubjecl:;
but it was notfo great a one as that,
'by which the faltpetre-makers were
permitted to dig up the floors of all
'dove-houfes, itables, &c. the pro-
prietors
* Rymer'sFced. Tom. XVIIII.p, 813.
( 238 )
prfetors being at the fame time pro-
hibited from the laying of fuch floors
with any thing but mellow earth.
To this grievance all perfons had
been fubjefted by a proclamation in
1625, which was revived in its chief
extent in 1634, the new invention
not having anfwered the purpofe for
which the patent had been granted ;
and it was not till the year 1656, that
an acl of parliament paffed, forbid-
ding the faltpetre-makers to dig in
houfes or lands, without leave of
the owners.
As in England the earth impreg-
nated with the dung of pigeons, the
urine of cattle, &c. was formerly fup-
pofed to belong to the crown ; fo in
France, the rubbifh. of all old houfes,
the mellow earth of llables, cellars,
&c, docs at prefent belong to the
king.
( 459 )
king. In the dominions of the kin*
of Pruflia, and in many parts of Ger-
many, the inhabitants are obliged
to build mud walls of any fat earth
mixed with ftraw ; and thefe wall?,
in a longer or Ihorter time, accord-
ing to the quality of the materials of
which they are built, and the fitua-
tion in which they are placed, be-
come impregnated with faltpetre.
There are a great many materials
from which faltpetre may be made;
in general, all animal and vegetable
fubftances, when mixed with iime-
ftone earths, or marles of different
forts, in fuch proportion as to excite
a putrefaction in the mafs, are pro*
per for this end. The parts of ani-
mals, without any addition of earth,
are faid to yield faltpetre by putre-
faction ; urine (lightly putrefied gives
VOL. i. T fait-
iVkpetre in a imall quantity; being
fully putrefied it yields it more abun-
;da nt 1 y * . K u n c ke 1 t o ok f i e fh b 1 ood,
and left it to putrefy in a warm place
till it was reduced to earth ; he ob-
tained, by this means, above five
pounds of fahpetrefrorn one hundred
pounds of blood f. If this experi-
ment may be generally relied on, ic
might, perhaps, be worth while to
txtracl the faltpetre from the earth
remaining in the blood and garbage
holes of fiaughter-houfes, The me-
thod of extracting faltpetre from
the earths in which it is generated,
is much the fame in all countries.
It confifts in pouring water upon the
earths, to diflblveallthefalt, of what-.
tver kind, which is contained in
them 3 in palling this water through
wood-
* Kunck. Chun. Vol. II, p. 296.
fid.?. ^3£-
wood-afhes, in order to- fupply
unformed parts of the falt-petre with
a proper alkaline bafis, and in eva-
porating the folution, till in be of
a proper ftrength to fnoot in:o
cryftais. The fakpetre obtained
by this fir ft cryflaliization, isfel-
clom pure enough for the pur-
pofes of making gunpowder, or of
medicine * .
I do not know that we have at
prefent any faltpetre works cftablifli-
-ed in England. There have teen
many projects propofed for making
it, both in the laft and prefent cen-
T 2 tury,
* The reader who wifiies to know more of
the manner of making (hl-tpetre, may con-
ftilt a very good paper of Mr. Henfhavrs, in
Bifliop Sprat's Hillory of the Royal Society,
p. 260 ; or Newman's CheiTnilry, publlfhed
by Lewis, p. 197 ; or Glauber's Prosperity
•of Germany; or Clarke's Nat. Bift. of Salt-
petre : the manner of making it in Pcdolhi
as defcribed in Philof. Tranf. 1.763.
tury, but they have all ended more
to the difadvantage than the emolu-
ment of the undertakers. The Socie-
ty for the Fncouragement of Arts and
Manufactures in vain propofed pre-
miums for the making of faltpetre,
from the year 1756 to 1764* : thefe
premiums were never claimed, and a
iahpetre work which was, about that
time, eftablifhed at the expence of
above fix t(jonfand pounds, was at lad
abandoned ; *the proprietors having
been experimentally convinced, that
they could not afford to fell their
faltpetre for Ids than four times the
price of that imported from India.
'1 he reafon of this conflant failure
in allanemprs to make faltpetre, with
profit in England, may be attributed
partly
* Doffc's Memoirs of Agriculture, VoU
. " ni .3U'bt»liod br
tfBWJMTT o
(
ti D^on-3 I IB
~TJ (omS
partly to the nature of the climate/
which probably does not generate
faltpetre fo abundantly as fome
other climates do; but principally,
it is apprehended, to the dearnefs
of the WQod-afh.es generally ufed in
preparing this fubftance, and to the
high price of the labour which muft
be employed in collecting and ma-
nufacturing the materials.
How far wood- allies are in all
cafes necefiary for the extraction ofv
iahpetre from the earths containing
ir, may be much queftioned from the
refult of the following experiment.
From an old barn, belonging to
the Dean and Chapter at Ely, I took '
fome decayed mortar, which was full
of thofe faline (hoots frequently fcea
on old walls, and boiled it in a pn>x
per quantity of water. The water be-
^ 3 ing
ing filtered and evaporated, afforded*
m great plenty,: fine well-formed
cryfcals of faitpetre : the cryftals were
taken out and dried, and the remain-
ing part of the folution was again
evaporated, and k again yielded very
good faltpetre : but I could not ob-
ferve that there was any occafion for
wood-allies to make any pare of the
folution cryilallize, or that there
were formed any cryftals either of
fea-falt, or of anf other fait, except
faltpetre.
This experiment, which-I repeated
raore than once, eontradi^s a very
generally received opinion, namely,
that faltpetre cannot be made from
therubbifh of old buildings, without
the concurrence of the fait feparable
from the afhes of burnt vegetables *.
It
* — nulluoi nit rum a nobis hie in Eu-
ropa
( 2.95 )
It cannot be denied, that the vegeta-
ble fixed alkali is one of the con'fti-
tuent parts of faltpetre ; but it is con-
tended, that the burning of vegeta-
bles is nor the only way of procuring,
that alkali, finee we fee, from this
experiment., that it was as certainly-
formed in the mortar as the foltpetre
itfelf was.
A few years ago, as feme workmen
were digging gravel near Bury •$!'.
Ed:i!i'.na*s> they met with a large folid
fubflance of a white colour, fur-
T 4 rounded^
ropa natiKn cogncici, cisjus nntivitatera non
mgrcditur f^i ftxus, qui in- cincribiis li.pnoriim.-
t> j j > i o
eom5uuOrum depre'icniiiuir. Boerh, Chen;..
Vol. II. t>. 336. Nruiire affords no- v
tikpctrc^— V. 'c may- be allured, that cry Hal-
line nitre, whcnceibsver it coraesy ha* been
iiVanui'aclured by ;ui ; that art has fupplied its
Alkaline I afis.y and reduced it into a, cryllalline-
fonn. Newman's Chcin^ p. .19.7.:
( C aafci ) )
rounded every way with gravel, and
at the diftance of twelve or fourteen
feet from the furface. They at rlrft
iniftook it for a lump of chalk $ Jlj^tjo
upon tatting it, they found.it to have
the tafte of fahpetre. 1 have a piece
of the original lump in my polTeffion.
It is a folio mafs, very harxj ; when
diflblved and cryflallized, it affords
cryflals, refembling in all their pro-
perties the pureft faltpetre. Unlefs
more care had been taken in examin-
ing the fifuation of this Jump of
faltpetre, when it was firft difcover-
ed, it may be difficult to account for
its production j but it is highly pro-
bable, that it was a natural produc-
tion, and that the afhes of burnt ve-
getables had never been employed in
its formation. The roots of horfe-
radi(h penetrate very deep into the
earth
y
earth; and uport inquky -I found/'
that> hofferadvfk -grfe^^^n the
furface of the earth where this mafs
of falt-petre was formed. Whether
this plant had contributed to its for-
mation, may be a queftion worthy
the reader's confideration, fince we
know that many plants, fuch as
borage, fennel, the fun-flower, and
tobacoo, yield faltpetre.
Another obfervation, which may
be drawn from what has been ad-
vanced, refpecls the nature of thofe
faline effiorefcences which were
found in the mortar, and are fre-
quently to be met with on old damp
walls, and from which the word falt-
petre, or fait of ftone (fal t>etr<e)>
feems to be derived. Many authors *
have
* See a paper of the very ingenious Du
Brown-
t 293 )
have affirmed, that the fa ft of
thefe fhoots is th<e mineral fixed
alkali. 1 have rpafon, from my own-
experiments on the fubjtcb, to be-
lieve, that the affirmation is true
in forrre inilances j but ic rnuft not,.
I apprehend, be generally admitted,,
fince we have feen that thofe fhoots
yield^ in feme circumftances, not
the mineral alkali, but a perfect fait-
fetre.
With great diffidence I propofe it
to be confidered, whether the fame
faline fliootsr which in fome cafes
conftitute the mineral fix.d a-lkal^
would not, if left to thcmfeives on
the fame place where they are pro-
duced, be at length converted into--
faltpetre. The operation of nature
in.
Brownrig ra Fli'lcf. Tranf. for 1774,, p. 485.
*— Opus Chyrn. by Marggraaf, Vol. IL
p. 419, — Cronite'dt*s Miner. p» 143^
in fpontaneoufly producing thofe
ihoots of mineral fixed alkali, is in
no refbecl; lefs wonderful than the
conversion of the fixed alkali itfelf,
by a longer procefs, into faltpetre.
This conjecture, founded on the dif-
ferent qualities of thefe faime {hoots*
and th.e manner of their being pro-
duced, may receive fame confirma-
tion from the two following facts.
cc Near the city of Xsn &' in China.
is a town, about which the land pro-
duces three things. One is the foap
they ufe there, called Kiev ; they
know nothing of ours. After it
has rained, if the fun fliine, there rife
out of the earth certain bladders of
thick froth, which are gathered to
wafh and whiten linen. The fecond
isjaltpetre9 and common Jalt the third..
Out of twenty pounds of earth, put
into
. u-
into a jar, and wrought after their
manner, they get twelve pounds of
fait, and three of falcjflffl©*
probable, that the Kie^ hjffifc
of, as fupplying the place of foap,
confifts in part or wholly of the
mineral fixed alkali. " Upon th^
coaft of Coromandel, in a fandy foilp?
not far from the fea, the inhabitants
gather, every morning, an earth
abounding with a natural alkali; of
this earth they make a ley, which
being fharpened by quick-lime, they
ufe in fixing their colours on their
linen cloths. But if the alkali l^d)
left undifturbed upon the place
J«Tp
where it is produced, it fpontane-
oufly changes itfelf into faltpetre-f."
If
* Churchill's Coll. of Travels, Vol. I.
p. 49.
•j. *— — . ft vero fao generationis loco relin-
( 301 )
If this Tandy earth was vvalhed, corn-
t r yx *« \t? o fi 5* ^ ^\4.
mon fait and faltpetre might proba-
bly be feparated from it, as is done
from the Chinefe earth before men-
tioned, and the two accounts con-
firm one another. If thefe accounts
be
qnittir alcali pttedi&um, fpante in nltrum le
tranfmutat. Mifcell. Cur. Germ. arm.
9 & 10, p. 460. There is an account in the
Philofophical Tranfactions for 1771, 1x567,
of a fertile alkaline fait, found in the country
of Tripoli in Barbary, which our callico-
printers thought anfwered their purpofes
better than any other fait they had ever
tried. This obfervation confirms what is
faid of the life of this fait found on the coaft
of Coromandel, and teaches us to attribute
the excellency of the Eaft India colours to
the nature of the alkali ufed in fix ng them.
The French dyers ufe an alkali prepared
from the burning of tartar and lees of wine :
this alkali is of the pureft kind ; and the fu-
periority of their colours over thofe of mofl
other countries, has been attributed to the
great purity of the alkali which they ufed,
Memoires de Chem. Vol. II. p. 556.
be admitted, they will- greatly tend
to reconcile the different opinions
of chemifls concerning the nitre or
matron of the ancients j fome hold-
ing it to have been the mineral
fixed alkali, and others efleeming
it the fame with our faltpetre ; for
it may in fact have been either one
or the other, or a mixture of both,
according to its age.
It may in the lafl place be re-
marked, that lea fait does not al-
ways accompany faltpetre in the
earths where it is generated, flnce
not a grain of fea fait could he ob-
tained from a large portion of the
decayed mortar. From the great
quantities of fea fait ufually i
in faltpetre earths, fome chemifts*
have conjectured, that fea fait was
in-
* Baumc Chy, Vol. Ill* p. 599.
C 303 )
infeniibly changed inro faitpetre ;
and others have fuppofed, that the
lame natural procefs which produced
faitpetre, produced alfo Tea fait.
The fore - mentioned experiment
renders this laft fuppofition fome-
whar doubtful ; the matter however
is not certainly eflablifhed either
way, and there is great room for
further inveftigaticn.
This leads us to the confideration
of a queftion of very difficult deci-
fion — how is faitpetre generated?
I am not afhamed to own my inabi-
lity to anfwer this queflion in a
manner fatisfaclory even to myfe-lf.
There are powers in nature in a
great meafure unknown to us, by
"which the parts of matter are fub-
jecbed to perpetual change, and
forced to alTume arrangements from
which new compounds are conftant-
( 304 )
ly refulting. The fweet, bitter,
and aromatic juices of vegetables,
the blood, bile, milk, urine, fat,
and bones of animals, are all of
them as different from the fubftances
from which they are compofcd, as
faltpetre is from the earth from
which it is generated : but the one
being a more common procefs of
nature than the other, it does not fo
much aftonifh us, or excite our cu-
ripfity to account for it. The an-
fwer of the Spaniard, who was afked
if he knew how the faltpetre was
yearly regenerated in his grounds,
feems to include all that philofophy
can fay on the fubject : " I have
two fields ; in the one I fow wheat,
and it grows; in the other I coi-
led faltpetre *."
* Hiftoire Nat. xde L'Efpagne, by Bowles,
p. 80.
There
( 305 )
There was a time when the alp
was looked upon, by all chemifts, as
the great ftorehoufe of faltpetre ;
and the earths in which it was found
were fuppofed to have attracted it,
ready formed, from the air. Inftead
of faltpetre in fubftance, fome later
philofophers have fuppofed that its
acid part only exifls in the air -, and
that this. acid part, being attracted
from the air, unites itfelf with the
earths which yield faltpetre. Others
are of opinion, that the acid of falt-
petre does not float in the air as a
fubftance diftinft from it, but that
it is one of the conflituent parts of
the air itfelf; and confequently, if
faltpetre be formed by the earths
attracting this acid, the air muft be
decompofed, I know not of any
VOL. i. U well"
tell ^conducted experiments, .xrftfch
^ne fo conclufive in favour of this'
aerial origiri of- faltpetre, as one of;
Lemery's-is againft it. He put.Jowe
lime into one difb, forne fait of tartar
into another, and a faltpetre earth,
from which he had extra&ed the
fait, into a third. He placed thefe
three dilhes in -a fituation open to the
accefs of the air, and fheltered from
the fun j he let them continue in that
fituation for two years; at the expi-
ration of that term he examined their
feveral contents, but no faltpetre
had been generated in any one of
them ; though faline ilioots had been
formed on the walls of the place in
which they flood. He afterwards
mixed thefe fame fubftances with
animal matters, and after they^Rad
Hood
flood a proper time, they all yielded
him faltpetre *.
Saltpetre, it is granted, cannot be
produced without air ; but a fimple
expofure to the air of the materials
in which it is mod generally found,
does not feem to be fufEcient for the
purpofe. Air is neceffary for the
commencing and continuing of that,
inteftine motion of the parts of ve-
getable and animal fubftances, which
is called putrefaction; and I do not
know whether the fame may not be
faid of fome minerals : hence, per-
haps, it may not be a proportion far
from the truth, if we fhould fay, that
faltpetre is never produced in fub-
fiances which have not undergone
a putrefactive fermentation. Thus
u 2 Lemery
* Memoires de 1* Academic des Scien. a
Paris ; ann. 1731.
( 3°8 )
iLtmery got faltpetre as foon as he
mixed with his earths animal fub-
ftances, which ever tend to putre-
faction. Frefh blood contains no
faltpetre, but Kunckel extracted a'
, large quantity from putrefied blood.
Frefh urine yields no faltpetre, but
putrefied urine yields it in great
abundance, as may be gathered from
the patent before mentioned, by
which it was ordered to be faved for
the making of faltpetre. Quick-
lime does not contain a particle of
faltpetre ; a mixture of frefh urine
and quicklime, if examined foon af-
ter it is made, will not yield any j
but after being fuffered to putrefy
for fix or feven months, very good
faltpetre may be extracted from it *.
All the common procefles for mak-
ing
* Chyraie par M, Baume, Vol. III. p. 594.
ing faltpetre imply the putrefa&iore
of the materials. Now if it be al-
lowed that faltpetre is never pro-
duced without fome kind and degree
of putrefaction, it may deferve to be
inquired, whether in its mode of ge-
neration it has not fome relation to
two other fubitances univerfally pro-
duced by putrefaction ; I mean fixed'
air and volatile alkali. Many con-
jectures, not fufficiently warranted
by experiment to be laid before the
reader, prefent themfelves on this
head : one experiment, however^ I
will mention, efpecially as it is- ge-
nerally adduced by chemical; writers
in fupport of their theories, concern-
ing the origin and nature- of the ac;*c£
of faltpetre. When, faltpetre and
charcoal in, powder- ar.e thrown-,
gether upon a fire, or any
fubftance, the faitpetre is fuddenly
exploded, with a noife which is
ufually called detonation ; much air
is fet at liberty 3 there arifes a very
copious condcnfable fume, and there
remains, when the detonation is fi-
nifhed, a fixed alkali ; that is, there
remains one of the conftituent parts
of faitpetre ; the other part/ namely,
the acid, is difperfed with the fume.
This confiderable fume has been col-
lected, and it is faid to contain no-
thing but water, mixed accidentally
with a little, fixed alkali, which is
fuppofed to have proceeded from
the alkaline bafis of the nitre *. The
Tquor, thus collected, is called the
clyjjus of nitre. I have frequently
collected this liquor, and always
found that it abounded with volatile
alkali.
* Di&ion. of Chem. Art. Cfyfus.
alkali. This volatile alkali may be
rendered vifible in a concrete form,
by diftilling the clyflus with a gentle
heat. Is the nitrous acid formed
from an union of fixed air with vo-
latile alkali by means of putrefac-
tion ? What is fixed air, and what
is volatile alkali, and how are they
produced, are queftions which want
an explanation juft as much as what
is the acid of faltpetre, and how is
it produced ?
IT 4 ESSAY
ESSAY IX,
Of THE MANNER OF MAKING
PETRE IN THE EAST INDIES.
THE reader will not be dif-
pleafed with feeing fome of
the beft accounts which I have met
with in books on this fubjeft, in the
words of the feveral authors.
<c There is alfo a great deal of
faltpetre vended at Suratte, which is
made at dfmer.y 60 leagues from
Agra^ out of the fatteft ground, after
it has lain fallow a confiderable
time* They dig, certain trenches*
which, after they have filled with
fait earth, they let in as much wa-
ter as is fufficieht to reduce it to
the confiftency of broth ; and to
foak it the better, they frequently
tread it with their feet : when they
judge the wafer has "diflblved all the
faline fubftance that was in the earth,
they draw up the water into ano-
ther trench, where in fome time it
thickens, when they boil it like fair,
fcumming it continually, and Af-
terwards put it into earthen pots,
where the dregs being fettled to the
bottom, they take it out again, and
dry it to a hard fubtlance in the
fun*."
" The manner in which nitre is
originally obtained in the Eaft In-
dies,
* Harris's Collection of Voyages, Vol. IL
p. 128,
dies, is (as I have it on the authority
of a perfon of unqueftiori able vera-
city, who made it his parcicu.lar bufi-
nefs to procure a juft information)
according to the following account*
There is a very tall kind of grafs
growing in the country where the
nitre is produced ; which, being
burnt cuftomarily in the autumn,
forms beds of very large extent,
covered with fuch falts and earths,
refulting from the incineration, as
are the moft proper matrices for the
formation of the nitre. Thefe, ly-
ing all the winter on the fides of
hills expofed to the winds, confe-
quently collect the nitrous fpirit
from the air, in the fame manner
as when fpread by art with that in-
tent ; and produce great quantities
of nitre. After this a rainy feafon
enfues*
( 3*6 )
enfues, which wafhes the fait dowa
into the vallies ; where the folution-,
partly abforbed by the earth, and
partly flowing above it, is expofed
to the heat of the fun, that makes an
evaporation of the humidity, and
leaves the fait in a dry (late, either
commixed with the earth, or on the
furface of it ; and this is fometimes
artificially aflifted-, by turning the
rills of water as they delcend from
the higher grounds by proper tanks,
into places where the abforption of
it by the ground is prevented ; and
where therefore the fluid drying away
by infolation, produces a ftrong folu-
tion of the nitre ; which being taken
out and purified in that ftate, is after-
wards reduced into a eryftalline form
by evaporation *."
u Salt-
( 317 )
" Salt-petre is likewife the pro-
duce of Patna. It is extracted from a
clay, which is either black, whitifh,
or red. The manner of refining it,
is by digging a large pit, in which
this nitrous earth is depofited, and
diluted with a quantity of water,
which is kept flirred till it comes to
a confiftency. The water having
drawn out all the falts, and the
groffer parts fubfiding at the bot-
tom, the more fluid particles are
taken out and put into another pit
not fo large as the former. This
fubftance having undergone a fecond
purification, the clear water that
fwims on the top, and is totally im-
pregnated with nitre, is taken off and
boiled in caldrons ; it is fcummed
while it is boiling, and in a few
hours a nitrous fait is obtained in-
3 finitely
finitely fupcrior to any that is found
elfewhere *. The Europeans export
about ten millions of pounds for the
ufe of their fettlements in Afia, or
for home confumption in their re-
fpective countries. It is bought upon
the fpot for three fols (id. \) a pound
at the moft, and is fold again to us
for ten (5d.) at the lead f."
By the inquiries which I have had
an opportunity of making, from
gentlemen who had long refided in
the Eafl Indies, I can only learn,
that there are certain earths naturally
impregnated with faltpetre, and that
the inhabitants throw up thefe earths
in
* lam ignorant of the 'particulars in which
the £aft India nitre excels that made in dif-
ferent parts of Europe.
t Hiftory of European Settlements in the
Eaft and Weft Indies. Eng. Tranf. Vol. I.
p. 340.
in little heaps, refembling the heaps
in which lime is ufually fcattered
over a field before it is fpread ; and
at a proper feafon they ex trad: the
faltpetre, and cryftallize it without
making any ufe of the alhes of burnt
vegetables. This method of making
faltpetre is much the fame with that
practifed in Egypt, as defcrjbed by
an author near an hundred years
ago. The furface of the earth, we
are told, where faltpetre is found,
is in fome places covered with a
whitilh cruft ; in others, the fait is
difcovered by the tafte of the earth.
This earth is dug up? and, being
parTed through a fieve, they deep
it in water, and then boil the wa-
ter tilK the fait falls to the bot-
tom. All the gunpowder made in
ggypt was formerly made of this
j fait-
Saltpetre * ; which Ihews the fait
thus procured to have been not the
mineral alkali, but a true faltpetre.
That this is a very pofiible me-
thod of making faltpetre is certain^
not only from the experiment with
the old mortar mentioned in the pre-
ceding Efiay, but from what is con-
ftantly pra&ifed in Spain, where
they extract large quantities of fait*
petre from earths naturally impreg-
nated with It, without having re-
courfe to vegetable afhes. A third
part of the uncultivated lands in
Spain, is faid to abound with falt-
petre ready foirned. Thefe lands,
where they are wrought for faltpetre,
are turned over two or three times
in
* Toute la poudre qu'on fait en Egypte
ti'eft fait que de ce nitre, qm eft le vray fal-
petre. Journ. des S^avans, 1685.
( 3*1 )
In the winter, and fpring; and in
Augufl they throw the earth in heaps,
and extract the faltpetre by pouring
water on the earth, put into proper
vefTels, and cryftallizing the folu-
tion. The earth, after the extrac-
tion of the faltpetre, is fpread en
the fame ground from which it was
taken, and at the expiration of
twelve months it again becomes
impregnated with faltpetre, and
the fame earths have for time im-
memorial annually produced the
fame quantity of faltpetre *. This
Spanilh earth refembles the Ghi-
nefe earth, mentioned in the laft
Effay, in containing a large por-
tion of fea fait, for they obtain
from twenty to forty pounds of
* Hift. Nat. de 1' Efpag. p. 79. French
Tranf. 1778.
VOL. i. X com-
common fait from one hundred
pounds of the earth : the etude falt-
petre alfo, as brought from the In-
dies, is greatly polluted with com-
mon fait. — Is the common fait in the
Spanifh earth annually regenerated
as well as the Ja Itpctre ?
The lands in Spain, fays the au-
thor of its Natural Hiftory, if pro>-
perly managed, -would fupply all
Europe ivith faltpetre to the end of
the world. In this circum fiance
Spain is more fortunate than Eng-
land, as we are obliged to rely upon
our importation from the Eaft Indies
for all the faltpetre we ufe. Spain
however has not yet been able, or
willing, to furniih from its lands,
faltpetre enough for its own con-
fumption; fince it is obliged, occa-
fionally, to have recourfe to an im-
4 portation
( 3*3 )
portation of that commodity' from
this kingdom.
The Eaft-India company had their
firft charter granted in 1600 : in the
year 1628 they publifhed their peti-
tion and remonftrance to the Houfe
of Commons. From this trad: it
appears, that they had a good quantity
of faltpetre then in ftore, and that
they weekly made about thirty bar-
rels of gunpowder at their own pow-
der mills, from fuch refined falt-
petre as they brought from the
Indies. By their charter, granted
in 1693, they were bound annually
to fupply government with 500 tons
of faltpetre at 38!. los. a ton in
time of peace, and at 45!. in time
of war.
The following tables were ex-
traded from the euilom-houfe books,
x ^ by
by a perfon on whofe
could depend.
Saltpetre imported annually into.
England for feven years ending at
Chriftmas 1769.
C. q. Ib.
From Xtmas 176210X1111. 1763— 42580 2 26
1764 — 22692 3 6
*76 5—3 5399 3 7
1766—41313 o o
3 2
1769—34437 3 o
Total imported in 7 years— 2 47689 3 3
This quantity gives an annual
medium of 396303610 *.
About
* The Dutch Eaft India fleet in 1 709, im-
ported 2175370 Ib. of faltpetre (Schelhamer
de nitro, p. 82) ; yet notwithflanding the
great quantities of faltpetre which'are annually
brought into Europe from the Eaft Indies, it
is reckoned that two-thirds of the whole pro-
duce of that- commodity are fent into China,
and
Saltj
to Chriftmas 1769.
Exported
Denmark and >
Eaft Country
Flanders
France *
Germany
Holland
Ireland
Italy
Portugal
Spain
Straights
Turkey
Antigua
Barbadoes
Canada
Carolina
Georgia
Florida
Jamaica
New England
New York
Nova Scotia
Pennfylvania
St. Chriftopher
Virginia and M
1767.
:. q. Ib.
97 i 21
1760'.
C. q. Ib.
1769.
C. q. Ib.
634 2 0
603 o 4
473 i 7
119 3 17
74.2 I 12
296 2 O
115 o 15
103 o 14
1761 o ii
61 o 13
538 o 9
1609 3 2
59 o 27
20 o o
82 o o
i i 4
70 i o
60 o 8
020
4 o 21
4011
O 2 24
22 O IO
1 3 7
7 0 22
2 I IO
343 II
12 3 0
25 2 6
5 2 o
O 2 O
2 0 20
44 2 8
12 3 o
3 o 12
20 3 o
727
024
23 3 17
112
47 2 12
2 3 16
22 2 7
6 2 19
49 i 20
37 o o
43 o 2
48 2 10
549 i 3
972 3 2 4422 2 17
Total exp«
annual medium of 7C2,i681b
About the fame period that the
government of England bargained
with the Eaft India company for an
annual fupply of faltpetre, a much
larger quantity was made in France ;
an author of good credit * informing
us that in the year 1691 the faltpetre
which was made in the feveral dif-
tridts of that kingdom, amounted to
— 3647767.1 pounds. Thisisavaft
quantity, being nearly equal to the
average quantity annually imported
by our Eaft India company. The
French very wifely keep up their
eftablifhments for the making of falt-
petre; the revolutions which have
formerly taken place in India, ren-
der it not improbable, that fimilar
x 3 ones
and other parts of Alia, to be ufed in fire-
works.
* >See Memoires d* Artillerie par Sr. Suri-
rez, Tom. II. p. 104. Amfter. 1702.
ones may take place again ; and Eng-
land would feel the diftrefs which
would attend the non-importation of
faltpetre from the Eaft Indies, more
fenfibly than any other ftate in Eu-
rope. This danger has not been ad-
verted to by any Minifler; but if
the prevention of it fhould ever en-
gage the attention of the legiflature,
the methods of making faltpetre
which are followed in France, would
deferve to be conficlered. For my
own part I can have no doubt, that
a plan might be contrived for the
making of faltpetre'in every county
of this kingdom, by the very mo-
derate labour of thofe, whofe idle-
nefs is at prefent a burden to them-
felves, and a reproach to the police
of the community, the paupers of , the
feveral parilhes.
ESSAY
ESSAY X.
OF THE TIME WHEN GUNPOWD-ER
WAS DISCOVERED.
TH E hiftory of the difeovery
of gunpowder is involved in
much obfcunty; the moft ancient
authors differing from each other
in their accounts of this matter, and
many of them confounding two dif-
tindt inquiries; — the difeovery of
the competition of gunpowder ;-«
and the difeovery of the means
of applying it ta the purpofes of
war.
x Father
( 3*8 )
Father Kircber * affirms, that with-
out controyerfy we ought to attri-
bute the invention of gunpowder to
Bartbold Schwartz, or Earth old the
Black, , monk of Goflar in Ger-
many, and a profound alchemifl.
This man having mixed together,
with a medical view, nitre, fulphur,
and charcoal, a fpark accidentally fell
upon the mixture, blew up the pot
in which it was contained, and caufed
a dreadful explofion. The monk,
aftonilhed at the event, made feveral
repetitions of his experiment, and
thereby fully difcovered the nature
of gunpowder, in the year 1354..
Kircher gives us alfo, out of a very
old German book which he profefles-
to have read, a monkiih account of
the.firft ufe which Schwartz made of
his
* Kirch. Mun. Sub. p. 487.
( 329 ):
his gunpowder ; he employed it to
frighten fome robbers from their
haunts in the woods.
Sebaftian Munfter fays, that he was
well informed by a very eminent
phyfician, that the Danes ufed guns
in naval engagements in the year
1354, and that a chemift called
Schwartz was the firft inventor of
them-}-. PontanttSy the Danifh hifto-
rian, accedes to this opinion.
Polydore Vergil, who died in the
year 15555 attributes the difcovery
of gunpowder to fome very ignoble
German, whofe name he wifhes
might never be handed down to
pofterity.
f Achilles Gaflams medicinae do&or, et
hiftoriographus, diligentiffime fcripfit mihi,
Bombarclas anno Chrifti 1354, in ufu apud
mare Danicum fiiiiTe, primumque inventtirem
et autorem extitiffe chymiftam quendam no-
mine Bartholdum Schwartznm monachuru.
Munfter. Cofmogr. Univ. Lib. 3. C. 174.
( 33° )
pofterity. He further informs us,
that this German invented alfo au
iron tube, and taught the Venetians
the ufe of guns in the year 1380*.
This is the common account of
the difcovery of gunpowder ; its
truth however is rendered doubtful
by what follows.
The battle of CreJJy was fought in
the year 1346 ; and an hiilorian who
lived at that time is quoted by
Spondanus as affirming, that the
Engliih greatly increased the con-
fufion the French had been thrown
into, by difcharging upon them
from their cannon hot iron bullets-f-.
Three years before the battle of
CrefTy, the Moors were befieged
by
* PolycL Verg. de Invcn. Rerum, Lib. II.
C. XI.
f Spend. Ann. Eccl, ann. 1346.
by the Spaniards in the city of Alge-
ziras; and we learn from Mariana,
the Spanifh hiftorian, " that the
befieged did great harm among the
Chriftians*with iron bullets they fhot:"
the fame aqthor adds, " this is the
firft time we find any mention of
gunpowder and ball in our hifto-
ries*." The Earls of Derby and Sa-
lijbury are mentioned by Mariana as
having affifted at the.fiege of Alge^
ziras ; and as they returned to Eng-
land in the latter end of the year
1343, it is not an improbable con-
jedture, that, haying been witnefles
of the havock occafioned by the
Moorifh fire-arms, they brought the
fecret from Spain to England, and
introduced the ufe of artillery into
the Englifh army at the battle of
CrefTy.
* Mariana's Hift. of Spain, Eng. Tranf.
(33* )
Creffy. The ufe of guns in Spain
in the year 1343, is proof fufficient
either that Schwartz was not the in-
ventor of gunpowder, or that Kircher
and others are miflaken infixing his
difcovery fo late as the year 1354-
There is reafon, however, to -be-
lieve, that both gunpowder and guns,
were known in Germany at leaft
forty years before the period afligned
by the Spanilh hiftorian for their
firft introduction into Spain. In the
1
armoury at Arnberg^ in the Palatinate
of Bavaria, there is a piece of ord-
nance, on which is infcribed the year
I3°3*t • This is the eadieft account
I have
f_ Qriam opinionem (of Schwartz being the
inventor of gunpowder) generofiilimus Stetre- i
nius refutat, cum ex eo quod Ambergse Pala- T
tinatus Superioris in officina armorum reperia?
tur toroxentum militare'cui fit ahnils 1303 u£
fcriptus. AclaErud. 1769, p. 19.
( 333 )
I, have yet met with of the certain
ufe of gunpowder in war ; and it
feems probable enough, as the Pope
and the Duke of Bavaria are thought
to have been the firil princes who
made faltpetre in Europe*.
It ought not to be concealed from
the reader, that Camerarius quotes a
Danifh hiftorian as relating, that
Chrifto'pher, king of the Danes, was
killed in battle by the ftroke of a
gun, in the year i28o-j*. Upon exa-
mining the paflage quoted by Came-
rariusj, it is onl faid, that Cbrifto-
pber, the fen of king IValdemar^ was
killed
« Clarke's Nat. Hift. of Saltpetre.
•f Cranzius fcribit Chriftophorum Danortfm
regem in praelio bombardae i&u occifiim anno
1280. Camera. Hor. Subf. Con. p. 3. 312.
} Cranzius Vaada!. Lib. VIII, C. 23.
( 334 )
killed in the beginning of an engage-
ment by a gun, a warlike inftrument
then lately difcovered. Now it ap-
pears % that Waldemar, Chriflo-
pher's father, did not fuccced to the
crown of Denmark till the year 1332,
and thai his fon was killed in a naval
engagement feveral years afterwardsf ,
probably about the time affigned by
Munfter for the firft ufe of gunpow-
der in Denmark.
But we are able, upon good
grounds, to carry the difcovery of
gunpowder to a period antecedent
to the date of the Amberg piece of
ordnance ; and it is probable enough,
that its compofition was known long
before we read any thing of its ufe
in war.
Roger
* Cranzius Dania?. Lib. VII. C. 32.
f Id. Lib. VII. C. 38.
( 335 )
Roger Bacon died a- Oxford in
1292. In the printed copies of the
works of this renowne 1 Monk, there
are two or three pafTages, from which
it may faiily be infeired, that he
knew the coinpofition of gunpow-
der * ; and a nvanufcript: copy is faid
to ha\Te been feen -f, wherein Jaltpe-
tre, fulphur and charcoal are exprefsly
mention-
* In omnem d'fhmtiam quam volumus, pof-
lumns artiftciaiirer componere ignem combu-
rentem ex iale petrte et aliis. R. Bacon de
Mirab. Potef. Artis et Nature. Epif. C. VI.
—fed tamen falis petrte Luru <vopo vir Can
Mriet fulpburis et fie facies tunitrum e( coruf-
cationem, ii icias artificium. Id. ib. C. XL
It is very probable, that in the firft of thefe
pafTages, Bacon concealed fulphur and char-
coal under the word aliis ; and that in the lafr,
having mentioned faltpetre and fulphur, he
concealed charcoal and the method of mixing
the three ingredients, under the barbarous
terms, Luru vopo vir can utriet.
. f Plott's N7at. Hift. of Oxfordfhire.
( 336 )
mentioned, as the ingredients of a
competition which would burn at
any diftance. But though it be al-
lowed, that Bacon was well acquaint-
ed with the compofition of gun-
powder, it will not follow, either
that he was the firft difcoverer of it,
or that he knew its application to
fire-arms.
The Moors, we have feen, who
had fettled in Spain, are efteemed
by fome to have been the firft per-
fons who ufed gunpowder in the
pra&ice of war ; they alfo brought
into Europe a great many Arabian
books, and introduced a tafte for che-
rrr.ftry into different countries, about
the time in which Bacon flourished.
It isconfdTed, on all hands, that Ba-
con was no flranger to Arabian lite-
rature ; a great part of his optical
dif-
( 337 )
difquifitions, being evidently bor-
rowed from Albazen the Arab; and
it is not a fuppofition wholly void
of probability, that he derived his
knowledge of the compofitton of
gunpowder from the fame fource.
As to his- knowledge of the ufe of
it in war, he certainly had fome
idea of its for he intimates, that
cities and armies might be deftroy-
ed by it in various ways : but it is
not equally certain that he had any
fpecific notion of the manner of
ufing gunpowder, which unquef-
tionably prevailed foon after his
death.
It is one thing to throw out a
conjecture concerning the effecls
which might be produced by the
proper application of a~ known fub-
ftance; another, to defcribe the
I. Y means
( 33* )'••
means of applying it. There are-
fubftances in nature, from a com-
bination of which it is poffible to
deflroy a Ihip, or a citadel, or an
army, by a Ihower of liquid fire-
fpontaneoufly lighted in the air :
every peribn who is aware of the
dreadful fiery explofion which at-
tends the mixture of two or three
quarts of fpirit of turpentine with
ftrong acid of nitre, muft acknow-
ledge the truth of the afTertion ;
but the fimple knowledge of the
pofiibility of effecting fuch a de-
ftruction, is a very different matter
from the knowledge of its practi-
cability; though future ages may,
perhaps, invent as many different
ways of making thefe fubflances
unite in the air, fo as to fall down
in drops of fire, as have been in-
vented
C BJ9 )
yented of making gunpowder, a fad
inflrument of the deftruftion of
our fpecies fince the time of Ba-
con.
From the accounts given of the
attempts of Salmoneus and Caligula
to imitate thunder and lightning,
fome have been of opinion that
•gunpowder was known to the an-
cients * : be that as it may, we can-
not hefitate in admitting that it has
been long known in various parts
of Afia» It would be ufelefs to cite
a variety of authorities in proof of
this point; I will content myfelf
with that of Lord Bacon: — " Cer-
tain it is, that ordnance was knowa
* See Duten's Enquiry into the Difcove-
ries of the Moderns, p. 263. Englifh Tranf-
( 340 )
in the city of the Oxidrakes in
India; and was that which the Ma-
cedonians called thunder and light-
ning, and magick. And it is well
known that the ufe of ordnance
hath been in China above 2000
years V
One of the mod ufeful applica>
tions of gunpowder, is in the art
of mining. The hammer and me-
tallic wedges were probably the
firft inftruments which men ufed
for the fplitting of rocks. The
application of wooden wedges to
the fame purpofe, feems to have
been a more recent difcovery: it
is the property of dry wood to ex-
pand itfelf, when wetted with wa-
ter: miners have had ingenuity
enough to avail themfelves of this
pro-
* Bacon's Effay on the Viciflitude of Things.
property, for it is a praftice with
them to drive wedges of dry wood
into the natural -or artificial crevices
of rocks, and to moiften the wedges
with water. Wood, by imbibing
moifture, fwe^ls in every dimenfion;
and the force of this expanfion is
fufficient, in many cafes, to detach
large pieces from the main body of
a rock. But the expanfive force
of gunpowder is incomparably
greater than that of mpiftened
wood. There are different accounts
of the time when gunpowder, was
firft applied to the blafting of
rocks. <c Rofsler relates that in
1627, *he .blafting of mines was
brought from Hungary, and intro-
duced in. the German mines: but
Bayer fays, that in 1613, it was1 in'-
Y 3 ventfcd
( 342 )
vented by Martin Freygold at Frei-
berg*.
In anfwer to an inquiry which I
made concerning the time when
blafting was introduced at the fa-
mous copper mine at Effon in Staf-
fordjhirey I received the following
account from a very able and intel-
ligent peribn. " I can give you
a little better information concern-
ing the affair of blafting. 1 have
known that country where the mine
i«, above fifty years -, and have often
feen the frnith's ihop in which, tra-
dition fays, the firft' boring auger
that had ever been ufed in Eng-
land was made; and that the firft
fhot that was ever fired in Derby-
ihire or Staffordiliire, was fired in
this
* < See Travels through the Eannat^ &c. by
J&aron Born. Eng. Tranf. p. 19^2.
( 343 )
this very copper-mine at Ecton.
The inhabitants of Wctton (a vil-
lage adjoining to the mine) tell me
the auger was made by feme Ger-
man miners, fent for over by Prince
Rupert to work this copper mine at
Eclxm. The Prince (Rapin fays)
came into England in 1636, and was
ordered by the King to leave the
kingdom 1645; anc^ though he was
afterwards admiral under Charles
the Second,, it is mod probable the
miners came during his firft abode
in this kingdom. I am very well
convinced of the truth of the above
tradition, becaufe the fathers of my
informers might be very well ac-
quainted with the miners that in-
troduced blafting among them." In
addition to this account 1 would
obferve, that the manner of fplitting
y 4 rocks
( ' 344 ) )
rocks by gunpowder, as praftifed
at Lie-gey was publifhed by the Royal
Society in 1665; and that it was.
not till about the year 1684, that
the miners in Somerfetfhire began
to ufe gunpowder*. In the year
1668 Prince Roipert was chofen
governor of the Society for ibe Mines
Royal f; and as he lived fourteen
years after that appointment, it is
not improbable that he might fend
for the German miners in confe-
quence of his connection with that
fociety.
Before the 'difcovery of blafting
rocks by gunpowder, it was the
cuftom in our Englifh mines, as
well as in Germany, to fplit them by
wood fires. This method is minute-
* Fhilof. Tranf.
•j- Account of Mines, p. 20.
( 345 )
ly defcribed by Agricola-*, and it is
not yet wholly fallen into difufef.
-It is a very ancient mode of mining,
being mentioned by Diodorus Sicu-
lus, as pradifed in fome Egyptian
mines J: he gives us, in the place
here referred to, fuch a melancholy
account of the condition of the poor
flaves who were employed in thofe
mines, as mud make the heart of
every humane man, who has a ra-
tional refped for the natural rights
of every individual of our fpecies,
fwell with indignation, and thrill
with horror. Would to God, that
the clemency of the tafkmafters in
the mines of Peru, and in other fet^
dements of European Cbriftians*
could
* De Re Metal.
f Philof. Tranf. 1777, p. 414.
J Lib. III.
( 346 )
could induce us to believe that
Diodorus Siculus had exaggerated
the barbarity of Heathen policy!
But there is much to be done,
much, I fear, to be fufiered, by
all the Hates of Chriftendom, before
the Gofpel of Chrift can be faid to
be eftablifhed amonglr. them as a
rule of life influencing their con-
dud.
It is related of Hamribaly that he
opened himfelf a paffage through
the Alps, by applying fire and vi-
negar to the rocks which oppofed
his route. This mode of iplitting
rocks was* probably, not invented
by Hannibal -, he might have had
frequent opportunities of obferving
a fimilar practice in the filver
mines in Spain, which daily afford-
ed him three hundred pounds
weight
( 347 )
weight of filver*. There is no-
thing, indeed, faid of vinegar in
the defcription of the Egyptian
mines before mentioned ; but Pliny
exprefsly affirms, that it was the
quality of vinegar, when poured
upon rocks, to fplit fuch as an an-
tecedent fire had not fplit; and
that it was the cuftom of miners
to buril the rocks they men with,
by fire and vinegar f. • This ac-
count of Hannibal's ufing vinegar
in
* Mirum adhuc per Hifpanias ab Hanni-
bale inchoates puteos durare, fua ab mven-
toribus nomina habentes. Ex queis Eclulo
appellatur, hodieque, qui CCC pondo Han«
nibali fubminiftrabac indies ! Plin. Hift,
Nat. L. 33. S. 31.
f Saxa rumpit infufum (acetum) quae non
ruperit ignis antecedens. Plin. Nat. Hift.
L. 23. S. 27. &'L. 33. S. 21. where by Sllices
cannot be underftood what we call flints, iince
vinegar has no a&ion on flinta.
( 34* )
. ,- ,. . , „ oSfU e:
rn fphtting the rocks, is generally1
looked upon as fabulous: for my
part, I can eafily conceive, that a
few barrels of vinegar might have
been of great ufe, if the rocks
were of the limeftone kind; and,
whether they were fo or not, I
leave to be fettled by thofe, who
have vifited the place where this
famous attempt was made. Vine-
gar corrodes all forts of limeftone
and marble rocks ; and hence, being
introduced into the crack made
by the fire, it might he very effica-
cious in widening them, and ren-
dering the feparation ; of large
lumps by iron crows and wedges
more eafy. It is erroneoufly fup-
pofed, that a large quantity of
vinegar was requifite, for the vine-
gar did not reduce the whole mafs
of
( 349 )
of rocks into a pulp; fince Livy
, s. . - - * * '
clearly informs us, that after the
action of both the fire and vinegar,
'. ^ <3VI^^Jl£i3 '/lilfi^1 n»j i c' 4
they were obliged to open their
paflage by iron inftruments, which
would have been wholly unnecefTary,
had the main body of the rocks
been diflblved by the vinegar *«,VB5|_
* — ardentiaque faxa infufo aceto pratre-
faciunt. Ita torridam incendio rupera ferro
pandunt. Liv. Hiih 1. xxi. c. xxxvii.
d fanfi'i aiooi '
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